MODULE V - panacea.iitianspace.com

CCOONNTTEENNTTSS

BOTANY

S. No. Chapter Page No.

1. Microbes in Human Welfare 01–25

2. Strategies for Enhancement in Food Production 26–55

3. Organisms and Populations 56–99

4. Ecosystem 100–137

5. Biodiversity and Conservation 138-171

6. Environmental Issues 172-201

MODULE – V

INDEX

Topic Name Page No

Chapter at a Glance 01-13

Exercise 14-24

Level-I 14-15

Level-II 16-18

Assertion & Reasoning 19-19

Previous Year’s Questions 20-24

Answer 25-25

This Chapter Includes:

Microbes in household products

Microbes in industrial products

Fermentation process

Fermented beverages

Antibiotics

Chemicals, enzymes and other bioactive molecules

Single cell proteins

Microbes in sewage treatment

Microbes in production of biogas

Microbes as biocontrol agents

Biopesticides

Bioherbicides and biological control of weeds

Microbes as biofertilisers

Economic importance of important bacteria

MICROBES IN HUMAN WELFARE

Microbes in Human Welfare Rg.-Bot. XII-19-21

COLLEGES: ANDHERI / BORIVALI / CHEMBUR / DADAR / KALYAN / KHARGHAR / NERUL / POWAI / THANE 1

Besides macroscopic plants and animals, microbes are the major components of biological

systems on this earth. Microbes are present everywhere – in soil, water, air, inside our

bodies and that of other animals and plants. They are present even at sites where no other

life-form could possibly exist–sites such as deep inside the geysers (thermal vents) where

the temperature may be as high as 100°C, deep in the soil, under the layers of snow several

meters thick, and in highly acidic environments. Microorganisms are generally single celled

or unicellular in nature. Microbes are diverse–protozoa, bacteria, fungi and microscopic

plants, viruses, viroids and also prions that are proteinaceous infectious agents. Some of the

microbes are shown in figures.

Bacteria : (a) Rod – shaped, magnified 1500 X; (b) Spherical shaped, magnified 1500 X; (c) A rod shaped bacterium showing flagella, magnified 50,000 X

Viruses : (a) A bacteriophage; (b) Adenovirus which causes respiratory infections; (c) Rod shaped Tobacco mosaic Virus (TMV). Magnified about 1,00,000 – 1,50,000X

Microbes like bacteria and many fungi can be grown on nutritive media to form colonies that

can be seen with the naked eyes. Such cultures are useful in studies of micro-organisms.

(a) Colonies of bacteria growing in a petri dish; (b) Fungal colony growing in a petri dish

MICROBES IN HUMAN WELFARE



Microbes cause a large number of diseases in human beings. They also cause

diseases in animals and plants. Several microbes are useful to man in diverse ways.

Some of the most important contributions of microbes to human welfare are discussed

in this chapter.

MICROBES IN HOUSEHOLD PRODUCTS

We use microbes or products derived from them every day.

CURD

A common example is the production of curd from milk. Micro-organisms such as

Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and

convert it to curd. During growth, the LAB produce acids that coagulate and partially digest

the milk proteins. A small amount of curd added to the fresh milk as inoculum or starter

contain millions of LAB, which at suitable temperatures multiply, thus converting milk to curd,

which also improves its nutritional quality by increasing vitamin B12. In our stomach too,

the LAB play very beneficial role in checking disease causing microbes.

YOGHURT

It is fermented milk. It is made from milk, skimmed milk or flavoured milk.

The fermentation is carried out by Streptococcus salivarius sub spp thermophilus and

Lactobacillus dulbruckii sub spp bulgaricus together at a level of 2% by volume. These

bacteria are called lactic acid bacteria (LAB) because they convert milk sugar lactose into

lactic acid. The LAB also improves its nutritional quality by increasing vitamin B12.

PH decrease from a level of 6.3 - 6.5 (milk) to 4.6 - 4.7 during the fermentation process. The

flavour in yoghurt is due to acetaldehyde which is about 23 - 41 mg/kg. Both the organisms

are lacking in alcohol dehydrogenase and produce acetaldehyde from glucose portion of

lactose via pyruvate and due to the action of enzyme threonine aldolase.

BREAD

The dough, which is used for making foods such as dosa and idli is also fermented by

bacteria. The puffed-up appearance of dough is due to the production of CO2 gas. Similarly

the dough, which is used for making bread, is fermented using baker’s yeast

(Saccharomyces cerevisiae).

DRINKS

A number of traditional drinks and foods are also made by fermentation by the microbes.

‘Toddy’, a traditional drink of some parts of southern India is made by fermenting sap from

palms using yeast. Fenny is made by fermenting cashewnuts. Sake is prepared by

fermenting rice using fungus Aspergillus in Japan.

Microbes are also used to ferment fish, soyabean and bamboo shoots to make foods.

Tempeh in Indonesia, Tofu in Japan and Sufu in China are fermented foods made from

soyabean.

CHEESE

Cheese, is one of the oldest food items in which microbes were used. Different varieties of

cheese are known by their characteristic texture, flavour and taste. The specificity comes

from the microbes used. For example, the large holes in ‘Swiss cheese’ are due to

production of a large amount of CO2 by a bacterium named Propionibacterium sharmanii.

The ‘Roquefort cheese’ are ripened by growing a specific fungi Penicillium roquefortii on

them, which gives them a particular flavour.

Camembert cheese or soft cheese (moisture content more then 50%) is prepared by using



the inoculum of Penicillium camemberti.

MICROBES IN INDUSTRIAL PRODUCTS

Even in industry, microbes are used to synthesise a number of products valuable to human

beings. Beverages and antibiotics are some examples. Production on an industrial scale,

requires growing microbes in very large vessels called fermentors.

Fermentors

The main function of fermentation is to provide a controlled environment for growth of a microorganism to obtain a desired product.

Different parts of fermentor (diagramatic, A) and a fermentor with multi blade impeller

(B)

FERMENTATION PROCESS

A. Batch process: In this process a large volume of nutrient medium (with volumes as large as 2,25000 litres) is inoculated and allowed to proceed until maximum yield has been obtained.

B. Continuous process: The fresh medium is added either continuously or intermittently accompanied by corresponding continuous or intermittent withdrawal of portion of a medium with the fermented product.



FERMENTED BEVERAGES

Microbes especially yeasts have been used from time immemorial for the production of

beverages like wine, beer, whisky, brandy or rum. For this purpose the same yeast

Saccharomyces cerevisiae used for bread-making and commonly called brewer’s yeast, is

used for fermenting malted cereals and fruit juices, to produce ethanol. Often yeast is added

in immobilized state in calcium alginate beads. Depending on the type of the raw material

used for fermentation and the type of processing (with or without distillation) different types of

alcoholic drinks are obtained. The nutrient medium is barley for beer, rye for gin, potato for

vodka, molasses for rum, cereals for whisky and fruit juices for wines and brandy. Wine and

beer are produced without distillation whereas whisky, brandy and rum are produced by

distillation of the fermented broth.

The photograph of a fermentation plant is shown in Figure

Fermentation Plant

ANTIBIOTICS

Antibiotics produced by microbes are regarded as one of the most significant discoveries

of the twentieth century and have greatly contributed towards the welfare of the human

society.

Anti is a Greek word that means ‘against’, and bio means ‘life’, together they mean

‘against life’ (in the context of disease causing organisms); whereas with reference to

human beings, they are ‘pro life’ and not against.

Antibiotics are chemical substances, which are produced by some microbes and can kill or

retard the growth of other (disease-causing) microbes.

Penicillin was the first antibiotic to be discovered, and it was a chance discovery. Alexander

Flemming while working on Staphylococci bacteria, once observed a mould growing in one

of his unwashed culture plates around which Staphylococci could not grow. He found out



that it was due to a chemical produced by the mould and he named it Penicillin after the

mould Penicillium notatum. However, its full potential as an effective antibiotic was

established much later by Ernest Chain and Howard Florey. This antibiotic was extensively

used to treat American soldiers wounded in World War II. Fleming, Chain and Florey were

awarded the Nobel Prize in 1945, for this discovery.

Streptomyces griseus produces more than 41 antibiotics while Bacillus subtilis gives

about 60 antibiotics. Among eubacteria most antibiotics are got from Bacillus (70%)

and Psuedomonas (30%). Common antibiotic from lichens is usnic acid. Many fungi also

yield antibiotics.

Table : Some Clinically Important Antibiotics.

S.No Antibiotic Producer Organism Activity Aginst Mode of Action (inhibit)

1. Penicillin Penicillium chrysogenum

G + ve bacteria Cell wall Synthesis

2. Cephalosporin Cephalosporium acremonium

Broad spectrum

Cell wall Synthesis

3. Fumagillin Aspergillus fumigatus Cell wall Synthesis

4. Griseofulvin Pencillium groseofulvum

Dermatophitic fungi

Microtubule formation

5. Bacitracin Bacillus subtilis G + ve bacteria Cell wall synthesis

6. Polymyxin B B. Polymyxa G - ve bacteria Cell membrane

7. Amphotericin B Streptomyces nodosus Fungi Cell membrane

8. Erythromycin Streptomyces erythreus G + ve bacteria Protein synthesis

9. Neomycin S. fradiae Broad spectrum

Protein synthesis

10. Streptomycin S. griseus G - ve bacterium

Protein synthesis

11. Tetracycline S. ramosus Broad spectrum

Protein synthesis (oxytracycline or Terramycin)

S.No Antibiotic Producer Organism Activity Aginst Mode of Action (inhibit)

12. Vancomycin S. orientalis G + ve Bacteria Protein synthesis

13. Gentamycin Micromonospora purpurea

Broad spectrum

Protein synthesis

14. Rifamycin S. mediferranei Tuberculosis Protein synthesis

15. Gramicidin Bacillus brevis Deteriorates Cell membrane

16. Colymycin B. colistinus Deteriorates Cell membrane

17. Chloamphenicol S. venezulae Protein synthesis

18. Novobiocin S. niveus and S. spheroids

Inhibit DNA polymerization



• Chloramphenicol inhibits the activity of peptidyl transferase after binding to 50S subunit of bacterial ribosome during protein synthesis. It is bacteriostatic i.e after removal of drug the effect is soon reversed. However, its effect in eukaryotes is the same as in prokaryotes.

• Tetracyclines prevent the binding of aminoacyl tRNA to the A site of 30S ribosome. Moreover it can bind to several sites of both 30S and 50S subunits.

• Cycloheximide inhibits protein synthesis in eukaryotes but not in prokaryotes. It interferes in the activity of ribosome present in cytoplasm but not in mitochondria by binding with 80 S subunits and preventing the movement of mRNA.

• Puromycin binds to peptide with the C-terminus of growing polypeptide and results in

premature termination of polypeptide chain. It interacts with the P site of ribosome but not

with A site. It works equally well on 70S and 80S ribosomes.

• After Penicillin, other antibiotics were also purified from other microbes. Antibiotics have

greatly improved our capacity to treat deadly diseases such as plague, whooping cough

(kali khansi ), diphtheria (galghotu) and leprosy (kusht rog), which used to kill millions all

over the globe. Today, we cannot imagine a world without antibiotics.

Chemicals, Enzymes and other Bioactive Molecules

Microbes are also used for commercial and industrial production of certain chemicals like

organic acids, alcohols and enzymes. Examples of acid producers are Aspergillus niger (a

fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid; Clostridium butylicum

(a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid. Yeast

(Saccharomyces cerevisiae) is used for commercial production of ethanol.

Microbes are also used for production of enzymes. Lipases are used in detergent

formulations and are helpful in removing oily stains from the laundry. Bottled fruit juices

bought from the market are clearer as compared to those made at home. This is

because the bottled juices are clarified by the use of pectinases and proteases.

Lactases prevent crystal formation in icecreams and cheese. Rennet obtained from calf

stomach is used to prepare cheese.

Streptokinase produced by the bacterium Streptococcus and modified by genetic

engineering is used as a ‘clot buster’ for removing clots from the blood vessels of

patients who have undergone myocardial infraction leading to heart attack.

Another bioactive molecule, cyclosporin A, that is used as an immunosuppressive

agent in organ-transplant patients, is produced by the fungus Trichoderma

polysporum. Statins produced by the yeast Monascus purpureus have been

commercialised as blood-cholesterol lowering agents. It acts by competitively

inhibiting the enzyme responsible for synthesis of cholesterol.

SINGLE CELL PROTEIN

Microorganisms eg. bacteria (Methylophilus methylotrophus), Cyanobacteria (Spirulina),

yeast (Saccharomyces cereviseae, Candida utilis etc.), filamentous fungi (Fusarium

graminearum, Chaetomium cellulolyticum), algae (Chlorella, Scandesmus etc.) which can be

cultured on a commercial scale in a source or as animal feed are called single cell proteins

(SCP).

• The biomass obtained from unicellular microorganism is considered as SCP.

• The SCP is rich in high quality protein and poor in fat content. The microoganisms

used in the production of SCP are very fast growing and produce large amount SCP from

relatively very small area. SCP are grown on agricultural and organic wastes thus playing



a role in pollution management.

MICROBES IN SEWAGE TREATMENT

Large quantities of waste water are generated everyday in cities and towns. A major component of this waste water is human excreta. This municipal waste-water is also called sewage. It contains large amounts of organic matter and microbes. Many of which are pathogenic. This cannot be discharged into natural water bodies like rivers and streams directly. Before disposal, hence, sewage is treated in sewage treatment plants (STPs) to make it less polluting. Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage. This treatment is carried out in two stages:

Primary treatment : These treatment steps basically involve physical removal of particles – large and small – from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge, and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.

Secondary treatment or Biological treatment : The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it. This allows vigorous growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh like structures).

While growing, these microbes consume the major part of the organic matter in the effluent. This significantly reduces the BOD (biochemical oxygen demand) of the effluent. BOD refers to the amount of the oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.

The sewage water is treated till the BOD is reduced. The BOD test measures the rate of uptake of oxygen by micro-organisms in a sample of water and thus, indirectly, BOD is a measure of the organic matter present in the water. The greater the BOD of waste water, more is its polluting potential.

Once the BOD of sewage or waste water is reduced significantly, the effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters. Here, other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi in the sludge. During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide. These gases form biogas and can be used as source of energy as it is inflammable. The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams. An aerial view of such a plant is shown in Figure.



Secondary treatment

Tertiary treatment: Tertiary treatment is aimed to remove nonbiodegradable organic materials, heavy metals, and minerals. The salt of nitrogen and phosphorus must be removed because they cause eutrophication. Finally the sewage effluent is subjected to chemical treatment for disinfection before releasing it into natural water bodies.

Secondary sewage treatment

Microbes play a major role in treating millions of gallons of waste water everyday across the

globe. This methodology has been practiced for more than a century now, in almost all parts

of the world. Till date, no manmade technology has been able to rival the microbial treatment

of sewage.

Due to increasing urbanisation, sewage is being produced in much larger quantities than

ever before. However the number of sewage treatment plants has not increased enough to

treat such large quantities. So the untreated sewage is often discharged directly into rivers

leading to their pollution and increase in water-borne diseases.

The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna

Action Plan to save these major rivers of our country from pollution. Under these plans, it is

proposed to build a large number of sewage treatment plants so that only treated sewage

may be discharged in the rivers.



An aerial view of a sewage plant

MICROBES IN PRODUCTION OF BIOGAS

Biogas is a mixture of gases (containing predominantly methane) produced by the microbial

activity and which may be used as fuel. Microbes produce different types of gaseous end-

products during growth and metabolism.

The type of the gas produced depends upon the microbes and the organic substrates they

utilise. In the examples cited in relation to fermentation of dough, cheese making and

production of beverages, the main gas produced was CO2. However, certain bacteria, which

grow anaerobically on cellulosic material, produce large amount of methane along with CO2

and H2. These bacteria are collectively called methanogens, and one such common

bacterium is Methanobacterium. These bacteria are commonly found in the anaerobic sludge

during sewage treatment. These bacteria are also present in the rumen (a part of stomach)

of cattle. A lot of cellulosic material present in the food of cattle is also present in the rumen.

In rumen, these bacteria help in the breakdown of cellulose and play an important role in the

nutrition of cattle. Thus, the excreta (dung) of cattle, commonly called gobar, is rich in these

bacteria. Dung can be used for generation of biogas, commonly called gobar gas.

The biogas plant consists of a concrete tank (10-15 feet deep) in which bio-wastes are

collected and a slurry of dung is fed. A floating cover is placed over the slurry, which keeps

on rising as the gas is produced in the tank due to the microbial activity. The biogas plant has

an outlet, which is connected to a pipe to supply biogas to nearby houses. The spent slurry is

removed through another outlet and may be used as fertiliser.

Cattle dung is available in large quantities in rural areas where cattle are used for a variety of

purposes. So biogas plants are more often build in rural areas. The biogas thus produced is

used for cooking and lighting. The picture of a biogas plant is shown in figure.

The technology of biogas production was developed in India mainly due to the efforts of

Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission

(KVIC).

A typical biogas plant

MICROBES AS BIOCONTROL AGENTS

Biocontrol refers to the use of biological methods for controlling plant diseases and pests. In

modern society, these problems have been tackled increasingly by the use of chemicals –

insecticides and pesticides. These chemicals are toxic and extremely harmful, to human

beings and animals alike, and have been polluting our environment (soil, ground water),



fruits, vegetables and crop plants. Our soil is also polluted through our use of weedicides to

remove weeds.

Biological control of pests and diseases:

In agriculture, there is a method of controlling pests that relies on natural predation rather

than introduced chemicals.

A key belief of the organic farmer is that biodiversity furthers health. The more variety a

landscape has, the more sustainable it is. The organic farmer, therefore, works to create a

system where the insects that are sometimes called pests are not eradicated, but instead are

kept at manageable levels by a complex system of checks and balances within a living and

vibrant ecosystem. Contrary to the ‘conventional’ farming practices which often use chemical

methods to kill both useful and harmful life forms indiscriminately, this is a holistic approach

that seeks to develop an understanding of the webs of interaction between the myriad of

organisms that constitute the field fauna and flora.

The organic farmer holds the view that the eradication of the creatures that are often

described as pests is not only possible, but also undesirable, for without them the beneficial

predatory and parasitic insects which depend upon them as food or hosts would not be able

to survive. Thus, the use of biocontrol measures will greatly reduce our dependence on toxic

chemicals and pesticides.

An important part of the biological farming approach is to become familiar with the various life

forms that inhabit the field, predators as well as pests, and also their life cycles, patterns of

feeding and the habitats that they prefer. This will help develop appropriate means of

biocontrol.

The very familiar beetle with red and black markings – the Ladybird, and Dragonflies

are useful to get rid of aphids and mosquitoes, respectively.

An example of microbial biocontrol agents that can be introduced in order to control butterfly

caterpillars is the bacteria Bacillus thuringiensis (often written as Bt). These are available

in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants

such as Brassica and fruit trees, where these are eaten by the insect larvae. In the gut of the

larvae, the toxin is released and the larvae get killed. The bacterial disease will kill the

caterpillars, but leave other insects unharmed. Because of the development of methods of

genetic engineering in the last decade or so, the scientists have introduced B. thuringiensis

toxin genes into plants. Such plants are resistant to attack by insect pests. Bt-cotton is one

such example, which is being cultivated in some states of our country.

A biological control being developed for use in the treatment of plant disease is the

fungus Trichoderma. Trichoderma species are free-living fungi that are very common

in the root ecosystems. They are effective biocontrol agents of several plant

pathogens.

Baculoviruses are pathogens that attack insects and other arthropods. The majority

of baculoviruses used as biological control agents are in the genus

Nucleopolyhedrovirus. These viruses are excellent candidates for species-specific,

narrow spectrum insecticidal applications. They have been shown to have no

negative impacts on plants, mammals, birds, fish or even on non-target insects. This

is especially desirable when beneficial insects are being conserved to aid in an overall

integrated pest management (IPM) programme, or when an ecologically sensitive

area is being treated.



BIOPESTICIDES Biopesticides are pesticides of biological origin.

BIOHERBICIDES AND BIOLOGICAL CONTROL OF WEEDS Certain crop plants do not allow the weeds to grow nearby. They are called smoother crops, e.g. Barley, Rye, Sorghum, Millet, Sweet clover, Alfalfa. Another way of weed control is the introduction of specific insects which feed on the weeds. However, the herbivore has to be carefully evaluated so that it may not switch over to the useful plants in case the weeds get eliminated. Extensive growth of Opuntia in India and Australia was checked through the introduction of its natural herbivore, cochineal insect (Cactoblastosis cactorum). Growth of Hypericum perforatum weed was controlled by introduction of Chrysolina beetles in USA.

The first bioherbicide happened to be mycoherbicide. It was elaborated in 1981. The herbicide is Phytophthora palmivora. The fungus does not allow the milkweed vine to grow in Citrus orchards.

Fungal spores like Devine and Collego are used as weedicides.

Bioinsecticides Insecticides, and for that matter all pesticides, should be specific for target organisms, nontoxic to others, nonpersistent and biodegradable.

1. Predators. Destructive insects or plant pests can be brought under control through introduction of their natural predators. The predators should be specific and unable to harm the useful insects. Introduction of ladybugs (Lady Bird Beetles) and Praying Mantis has been successful in combating scale insects or aphids which feed on plant sap.

2. Intercropping. This keeps the population of insects at low level. In intercropping the crop favoured by particular insect pest is grown along with another which is normally repellent to the pest.

3. Insect hormones. Two types of insect hormones are used for controlling pests.

Sex pheromones are used in two ways; (a) Pheromone Traps. Traps containing hollow cylinders coated from inside with a sticky substance and sex pheromones are kept at different places in the fields. The male insects fly into the traps and get immobilised. As the males become unavailable for mating, the population of the insect will decline rapidly. Gypsy moth has been controlled by this technique. (b) Confusion Technique. Small pieces of unwettable paper containing sex pheromone of a particular insect are dropped over the fields. The males will not be able to locate the females because the pheromone is spread everywhere.

4. Natural Insecticides. Natural insecticides are specific in nature, nonpersistent, nontoxic to higher forms and easily biodegradable. A number of natural insecticides are available. The common ones include (i) Azadirachtin from Margosa or Neem - (Azadirachta indica). (ii) Pyrethrum. It is an insecticide which is obtained from the inflorescence of Chrysanthemum. (iii) Thurioside. It is a toxin produced by bacterium Bacillus thuringiensis (iv) Transgenic Plants. They are crop plants which are modified through genetic engineering to develop natural resistance to insects. Transgenic Tomato has been developed which is resistant to hornworm larvae.

Squill is a raticide got from sea onion Ureginea maritima.

Nicotine sulphate is one of the most toxic insecticides. It is obtained from Nicotiana

species.



Rotenone is powerful insecticide harmless to warm blooded animals and got from

roots of Derris elliptica.

MICROBES AS BIOFERTILISERS

Environmental pollution is a major cause of concern. The use of the chemical fertilisers to

meet the ever-increasing demand of agricultural produce has contributed significantly to this

pollution.

There are problems associated with the overuse of chemical fertilisers and there is a large

pressure to switch to organic farming and use biofertilisers.

Biofertilisers are organisms that enrich the nutrient quality of the soil. The main sources of

biofertilisers are bacteria, fungi and cyanobacteria. Nodules on the roots of leguminous

plants are formed by the symbiotic association of Rhizobium. These bacteria fix atmospheric

nitrogen into organic forms, which is used by the plant as nutrient. Other bacteria can fix

atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter),

thus enriching the nitrogen content of the soil. Fern Azolla is popularly grown in paddy fields

as biofertiliser as it has symbiotic association with BGA Anabaena in its roots making it a

rich source of nitrogen. BGA Aulosira fertilisiana is grown as biofertiliser in paddy fields.

Fungi are also known to form symbiotic associations with plants (mycorrhiza). Many

members of the genus Glomus form mycorrhiza. The fungal symbiont in these associations

absorbs phosphorus from soil and passes it to the plant. Plants having such associations

show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity

and drought, and an overall increase in plant growth and development.

Ectomycorrhiza. They perform several functions for the plant - (i) Absorption of water, (ii)

Solubilisation of organic matter of the soil humus, release of inorganic nutrients, absorption

and their transfer to root. (iii) Direct absorption of minerals from the soil over a large area and

sending over the same to the root. Plants with ectomycorrhiza are known to absorb 2-3 times

more of nitrogen, phosphorus, postassium and calcium, (iv) The fungus secretes

antimicrobial substances which protect the young roots from attack of pathogens.

Ectomycorrhiza occurs in the trees like Eucalyptus, Oak (Quercus), Peach, Pine, etc.

Endomycorrihiza. Endomycorrhiza is also called VAM or vesicular-arbuscular mycorrhiza.

The major benefits of VAM to the plant is the supply of inorganic nutrients as well as

enhanced water absorption. Phosphate which is mostly present in the unavailable form in the

soil, becomes abundantly available to the plant. Besides, the fungus provides various growth

promoting substances. Consequently, plants having endomycorrihizae show more vigorous

growth.

Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial

environments many of which can fix atmospheric nitrogen, e.g. Anabaena, Nostoc,

Oscillatoria, etc. In paddy fields, cyanobacteria serve as an important biofertiliser. Blue

green algae also add organic matter to the soil and increase its fertility. Currently, in our

country, a number of biofertilisers are available commercially in the market and farmers use

these regularly in their fields to replenish soil nutrients and to reduce dependence on

chemical fertilisers.



Economic importance of important bacteria:

S.No Products/Processes Bacteria

1. Preparation of acetone-butanol Clostridium acetobutylicum

2. Preparation of acetic acid/vinegar Acetobacter aceti

3. Preparation of lactic acid Lactobacillus delbruecki

4. Retting of fibres Clostridium butyricum

5. Curing of tobacco Bacillus megatherium

6. Curing of tea Mycococcus condisans Bacillus megatherium

7. Preparation of amino acid threonine Escherichia coli

8. Decomposition of DDT Aerobacter aerogenes

9. Decomposition of oil spills Psuedomonas putida(superbug)

10. Genetic engineering Agrobacterium tumefaciens Escherichia coli

11. Vitamin B2 (Riboflavin) Clostridium butylicum

12. Vitamin B12 Propionibacterium shermanii

13. SCP Methylophilus methylotropus



EXERCISE # LEVEL-I (CLASS WORK)

1. Name the blank spaces A, B, C and D given in the following table

Type of Microbe Scientific Name Commerical, Product Bacterium A Lactic acid Fungus B Cyclosporin A C Monascus purpureus Statins Fungus Penicilliium notatum D

(1) A – Lactobacillus, B – Trichoderma polysporum, C – Yeast (Fungus), D – Penicillin (2) A – Lactobacillus, B – Trichoderma polysporum, C – Yeast (Algae), D – Penicillin (3) A – Lactobacillus, B – Trichoderma polysporum, C – Yeast (Prokaryotic), D – Penicillin (4) A – Lactobacillus, B – Trichoderma polysporum, C – Agaricus (Fungus), D – Penicillin 2. Microbes are used in A. Primary treatment of sewage B. Secondary treatment of sewage C. anaerobic sludge digester D. production of bioactive molecules (1) A, C, D (2) A, B, C, D (3) B, C, D (4) C, D 3. Yeasts have been used for the commercial production of A. Wine B. Whisky C. Ethanol D. Curd (1) A, B, C (2) A, B, C, D’ (3) B, C, D (4) A, B, D 4. The distillation of the fermented broth is required in the formation of A. rum B. beer C. brandy D. whisky (1) A, B, C (2) A, C, D (3) B, C, D (4) A, B, D 5. Which of the following is used as biofertilizer? A. Cyanobacteria B. Yeast C. Symbiotic bacteria D. Free living bacteria (1) A, B, C (2) A, B, D (3) A, C, D (4) A, B, D 6. Symbiotic association is exhibited by A. mycorrhiza B. Rhizobium C. heterocyst D. Yeast (1) A, C, D (2) A, B, C, D (3) B, C, D (4) A, B 7. Methanogens grow anaerobically on cellulosic material and produce A. methane B. oxygen C. Carbon dioxide D. hydrogen (1) A, C, D (2) A, B, C, D (3) B, C, D (4) A, B 8. Methanogens are found in A. ethanol B. organic acids C. anaerobic sludge D. rumen of cattle (1) A, C, D (2) C, D (3) B, C, D (4) A, B 9. The technology of biogas production in India has been developed by the efforts of A. Khadi and Village Industries Commission (KVIC) B. Indian Council of Agricultural Research (IARI) C. Indian Agricultural Research Institute (IARI)



D. Indian council of Medical Research (ICMR) (1) A, C, D (2) C, D (3) A, C (4) A, B 10. Which of the following food items is produced by fermentation by the microbes? A. Idli B. Dosa C. Toddy D. Cheese (1) A, B, C, D (2) C, D (3) A, C (4) A, B, C 11. Which of the following bacteria convert milk into curd? (1) Propioniobacterium (2) Lactobacillus (3) Streptococcus (4) Bacillus 12. Which role is played by lactic acid bacteria (LAB) in our stomach? (1) Beneficial (2) Harmful (3) Neutral (4) All of these 13. The dough used for making bread is fermented by (1) bacteria (2) Yeast (3) fungi (4) algae 14. Which of the following is used in preparing cheese? (1) algae (b viruses (3) microbes (4) prions 15. The large vessels for growing microbes on an industrial scale are called (1) Petri dish (2) digestors (3) biogas vessel (4) fermentors 16. The gas responsible for puffing up appearance of dough comes from (1) aerobic respiration (2) fermentation (3) photosynthesis (4) photorespiration 17. The chemical substances produced by some microbes which can kill or retard the growth of

other microbes are called (1) toddy (2) lactic acid (3) antibiotics (4) ethanol 18. Which of the following antibiotics was discovered first? (1) Streptomycin (2) Neomycin (3) Erythromycin (4) Penicillin 19. Acetic acid is produced by a (1) fungus (2) bacterium (3) Yeast (4) virus 20. Which of the following bacteria has a role in removing clots from our blood vessels? (1) Bacillus thuringiensis (2) Clostridium butylicum (3) Streptococcus (4) Lactobacillus 21. Statins used for lowering blood-cholesterol level are extracted from – (1) algae (2) bacteria (3) virus (4) Yeast 22. The bioactive molecule cyclosporin A is used in – (1) whooping cough (2) diphtheria (3) leprosy (4) organ-transplant patients 23. The primary treatment of sewage involves – (1) digestion (2) decomposition (3) sedimentation and filtration (4) none of these 24. The symbiotic association between fungi and roots of higher plants is called – (1) lichen (2) mycorrhiza (3) biofertilizer (4) BOD 25. The organisms which are used to enrich the nutrient quality of the soil are called – (1) mycorrhiza (2) biofertilizers (3) Yeast (4) methanogens



LEVEL-II (HOME WORK)

1. During which stage of sewage treatment microbes are used?

(1) Primary treatment (2) Secondary treatment

(3) Tertiary treatment (4) All of these

2. Which antibiotic was extensively used to treat American soliders wounded in World War II?

(1) Terramycin (2) Erythromycin (3) chloromycetin (4) Penicillin

3. The solids which settle after primary treatment of sewage are called

(1) primary sludge (2) activated sludge

(3) flocs (4) total solids

4. Given below are three statements (A – B) each with one or more blanks. Select the option which correctly fills the blanks in the statements –

Statements:

A. Microbes consume the major part of the organic matter in the effluent and reduce ________ of sewage.

B. Certain bacteria which grow anaerobically on cellulosic material, produce large amount of methane along with CO2 and H2. The bacteria are commonly called as ________ and one such common bacterium is ________

Options:

(1) A – CO2 demand; B – methanogens, Methanobacterium

(2) A – Carbon; B – methanogens, methanobacterium

(3) A – biochemical oxygen demand; B-methanogens, Methanobacterium

(4) A – biochemical oxygen demand; B – methanogens, methylokorus infernorum

5. Given below are three statements (A – C) each with one or more blanks. Select the option which correctly fills the blanks in the statements –

Statements:

A. ___ a traditional drink of some parts of South India is made by fermenting sap from palms.

B. Citric acid is obtained through the fermentation carried out by _________ and _________ on sugary syrups.

C. In _________ the fungus forms a mantle on the surface of the roots.

Options:

(1) A – Toddy; B – Aspergillus niger, Mucor; C – Ectomycorrhiza

(2) A – Wine; B – Aspergillus niger, Rhizopus C – Ectomycorrhiza

(3) A – Beer; B – Aspergillus niger, Mucor; C – Endomycorrhiza

(4) A – Rum; B – Aspergillus niger, Mucor; C – Endomycorrhiza

6. The below diagram shows a typical biogas plant. Which of the following four option, products labeled as A, B and C are correctly identified –



(1) A – Sludge; B – methane, Oxygen; C – Dung, Water

(2) A – Sludge; B – methane, Carbon dioxide; C – Dung, Water

(3) A – Sludge; B – Ethylene, Carbon dioxide; C – Dung, water

(4) A – Sludge; B - methane, Carbon dioxide; C – Sewage

7. Column – I Column – II

I. Streptomyces A. Nitrogen fixation

II. Rhizobium B. Source of antibiotics

III. Nitrosomonas C. Vinegar synthesis

IV. Acetobacter D. Nitrification

(1) I – B, II – A, III – D, IV – C

(2) I – C, II – D, III – A, IV – B

(3) I – A, II – B, III – C, IV – D

(4) I – D, II – B, III – A, IV – C


I. Methanogens A. Microbial biocontrol agent

II. Organic wastes B. Penicillin

III. Bacillus thuringiensis C. Biochemical oxygen demand

IV. Penicillium notatum D. Methanobacterium

Which of the combinations is correct?

(1) I – B, II – A, III – D, IV – C

(2) I – C, II – D, III – A, IV – B

(3) I – D, II – C, III – A, IV – B

(4) I – D, II – B, III – A, IV – C


I. Fermentors A. Baker’s yeast

II. Bread B. Large vessels for growing microbes

III. Aerobic microbes C. Ministry of Environment and Forest

IV. Ganga Action Plan D. Flocs


(1) I – B, II – A, III – C, IV – D (2) I – C, II – D, III – A, IV – B

(3) I – A, II – B, III – C, IV – D (4) I – B, II – A, III – D, IV – C


I. Statins A. Yeast

II. Ethanol B. Blood-cholesterol lowering agent

III. Dung C. Insect-resistant plant

IV. Bt-cotton D. Biogas


(1) I – B, II – A, III – D, IV – C (2) I – C, II – D, III – A, IV – B

(3) I – A, II – B, III – C, IV – D (4) I – D, II – B, III – A, IV – C

11. Benefits of mycorrhizae are –

A. Resistance to root-borne pathogens

B. tolerance to salinity and absorption of phosphorus

C. Tolerance to drought

D. Overall increase in the plant growth and development

(1) Only A, B (2) Only B, C

(3) Only C, D (4) A, B, C, D



12. The vitamin whose content increases following the conversion of milk into curd by lactic acid bacteria is:

(1) vitamin C (2) vitamin D

(3) vitamin B12 (4) vitamin E.

13. Wastewater treatment generates a large quantity of sludge, which can be treated by:

(1) digesters (2) activated sludge

(3) chemicals (4) oxidation pond

14. Methanogenic bacteria are not found in:

(1) rumen of cattle (2) gobar gas plant

(3) bottom of water-logged paddy fields (4) activated sludge.

15. The primary treatment of waste water involves the removal of:

(1) dissolved impurities (2) stable particles

(3) toxic substances (4) harmful bacteria

16. BOD of waste water is estimated by measuring the amount of :

(1) total organic matter (2) biodegradable organic matter

(3) oxygen evolution (4) oxygen consumption.

17. Which one of the following alcoholic drinks is produced without distillation?

(1) Wine (2) Whisky

(3) Rum (4) Brandy

18. The free-living fungus Trichoderma can be used for:

(1) killing insects

(2) biological control of plant diseases

(3) controlling butterfly caterpillars

(4) producing antibiotics 19. What would happen if oxygen availability to activated sludge flocs is reduced? (1) It will slow down the rate of degradation of organic matter (2) The center of flocs will become anoxic, which would cause death of bacteria and

eventually breakage of flocs. (3) Flocs would increase in size as anaerobic bacteria would grow around flocs. (4) Protozoa would grow in large numbers. 20. Mycorrhiza does not help the host plant in: (1) Enhancing its phosphorus uptake capacity (2) Increasing its tolerance to drought (3) Enhancing its resistance to root pathogens (4) Increasing its resistance to insects. 21. Which one of the following is not a nitrogen-fixing organism? (1) Anabaena (2) Nostoc (3) Azotobacter (4) Pseudomonas 22. Big holes in Swiss cheese are made by a: (1) a machine (2) a bacterium that produces methane gas (3) a bacterium producing a large amount of carbon dioxide (4) a fungus that releases a lot of gases during its metabolic activities. 23. The residue left after methane production from cattle dung is: (1) burnt (2) buried in land fills (3) used as manure (4) used in civil construction. 24. Methanogens do not produce: (1) oxygen (2) methane (3) hydrogen sulfide (4) carbon dioxide. 25. Activated sludge should have the ability to settle quickly so that it can: (1) be rapidly pumped back from sedimentation tank to aeration tank (2) absorb pathogenic bacteria present in waste water while sinking to the bottom of the

settling tank



(3) be discarded and anaerobically digested (4) absorb colloidal organic matter.

ASSERTION & REASON ( CLASS WORK)

In the following questions a statement of assertion (1) is followed by a statement of reason (R).

(1) If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)

(2) If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2)

(3) If Assertion is true statement but Reason is false, then mark (3) (4) If both Assertion and Reason are false statements, then mark (4)

1. A : Spirulina is a single cell protein.

R : It is produced by plant breeding.

2. A : SCP can be produced using fungi, yeast and bacteria.

R : SCP is obtained from both uni and multicellular micro-organisms.

3. A : Sustainable agriculture is also known by the name of agro-farming.

R : It aims to increase agricultural productivity by the use of agro-chemicals.

4. A : Cry gene has insecticidal property.

R : It is responsible for the formation of crystal protein which is toxic for the insect digestion.

5. A : Cyclosporin A is produced by the fungus Trichoderma polysporum.

R : It is a bioactive molecule used as immunosuppressive agent in organ transplant patients.

6. A : LAB activity is beneficial for humans.

R : LAB causes harm in our stomach.

7. A : Cheese has characteristic texture, flavor and taste.

R : Microbes used determines texture, flavor and taste in cheese.

8. A : Antibiotics are beneficial for human being.

R : Antibiotic kills only harmful microorganisms.

9. A : Wine and beer is produced without distillation.

R : At 13% of ethanol concentration death of yeast takes place.

10. A : Bottled juice are clearer as compared to those made at home.

R : Pectinase and protease is used in bottled juice.

11. A : Cyanobacteria is widely used as a biofertilizer.

R : Cyanobacteria is autotrophic.



PREVIOUS YEARS QUESTIONS (HOME WORK)

1. A good producer of citric acid is :

(1) Saccharomyces (2) Aspergillus [NEET 2013]

(3) Pseudomonas (4) Clostridium

2. During sewage treatment, biogases, are produced which include:

(1) hydrogen sulphide, nitrogen, methane [NEET 2013]

(2) methane, hydrogen sulphide, carbon dioxide

(3) methane, oxygen, hydrogen sulphide

(4) hydrogen sulphide, methane, sulphur dioxide

3. Monoascus purpureus is a yeast used commercially in the production of [AIPMT 2012]

(1) Ethanol

(2) Streptokinase for removing clots from the blood vessels

(3) Citric acid

(4) Blood cholesterol lowering statins

4. Yeast is used in the production of

(1) Citric acid and lactic acid (2) Lipase and pectinase [AIPMT 2012]

(3) Bread and beer (4) Cheese and butter

5. Which one of the following is an example of carrying out biological control of pests / diseases using microbes?

(1) Trichoderma sp. against certain plant pathogens. [AIPMT 2012]

(2) Nucleopolyhedrovirus against white rust in Brassica.

(3) Bt. Cotton to increase cotton yield.

(4) Lady bird beetle against aphids in mustard.

6. The most abundant prokaryotes helpful to human in making curd from milk and in production of antibiotics are the one categorized as [AIPMT 2012]

(1) Cyanobacteria (2) Archaebacteria

(3) Chemosynthetic autotrophs (4) Heterotrophic bacteria

7. In gobar gas, the maximum amount is that of

(1) Butane (2) Methane [AIPMT 2012]

(3) Propane (4) Carbon dioxide

8. Trichoderma harzianum has been proved useful microorganism for the

(1) Bioremediation of contaminated soil. [UPCPMT 2012]

(2) Reclamation of waste lands.

(3) Gene transfer in higher plants.

(4) Biological control of soil borne plant pathogens.

9. Which of the following plants are used as green manure in crop fields and sandy soil?

(1) Crotalaria juncea and Alhagi camelorum [UPCPMT 2012]

(2) Calotropis procera and Phyllanths niruri

(3) Saccharum munja and Lantana camara



(4) Dichanthum annulatum and Azolla nilotica

10. Which one of the following help in absorption of phosphorus form soil by plants?

(1) Rhizobium (2) Frankia [UPCPMT 2012]

(3) Anabaena (4) Glomus

11. Which one of the following is not a biofertilizer?

(1) Rhizobium (2) Nostoc [AIIMS 2012]

(3) Mycorrhiza (4) Agrobacterium

12. Nitrifying bacteria

(1) Convert free nitrogen to nitrogen compounds [AIPMT 2011]

(2) Convert proteins into ammonia

(3) Reduce nitrates to free nitrogen

(4) Oxidize ammonia to nitrates

13. An organism used as a biofertilizer for raising soyabean crop production is [AIPMT 2011]

(1) Azospirillum (2) Rhizobium (3) Nostoc (4) Azotobacter

14. Ethanol is commercially produced through a particular species of [AIPMT 2011]

(1) Clostridium (2) Trichoderma

(3) Aspergillus (4) Saccharomyces

15. Rotenone is a

(1) Bioherbicide (2) Commonly used biofertilizer [DUMET 2011]

(3) Bioinsecticide (4) Juvenile hormone

16. Neem tree has acquired industrial importance as a source of [MHT CET 2011]

(1) Biofertilizer, biopesticide and anti-fertility compound

(2) Anti-fertility compound, biofertilizer and anti-cancer drug

(3) Biopesticide and anti-fertility compound

(4) Anti-cancer drug, biopesticide and biofertilizer

17. In paddy fields biological nitrogen fixation is chiefly brought by [RPMT 2011]

(1) Cyanobacteria (2) Green algae

(3) Mycorrhiza (4) Rhizobium

18. Bacillus thuringiensis is used as

(1) Biofungicide (2) Bioherbicide [OJEE 2010]

(3) Biocontroller (4) Bioweapon

19. Which of the following is not used as a biopesticide? [AIPMT 2009]

(1) Bacillus thuringiensis (2) Trichoderma harzianum

(3) Nuclear Polyhedrosis Virus (NPV) (4) Xanthomonas campestris

20. Which of the following herbicides and defoliant were used by the US military in its herbicidal warfare programme during the Vietanam war? [AFMC 2009]

(1) Agent black (2) Agent orange

(3) Super orange (4) Both (2) and (3)

21. Which of the following can be controlled by using biopesticides? [BHU 2009]

(1) Insects (2) Diseases

(3) Weeds (4) All of these

22. Which one of the following is not a biofertilizer? [DUMET 2008]

(1) Bacillus thuringiensis (2) Azotobacter

(3) Azolla (4) Clostridium



23. Which of the following insecticides is obtained from the roots of Derris elleptica?

(1) Cinerin (2) Nicotine [Manipal 2008]

(3) Rotenone (4) Pyrethrum

24. Gobar gas contains mainly [MHTCET 2008]

(1) CH4 and CO2 (2) CH4 and O2

(3) CH4 and H2 (4) CH4 and SO2

25. The plant most commonly used as green manure is [MHT CET 2008]

(1) Delbergia sissoo (2) Polyalthea

(3) Sesbania aculeate (4) None of these

26. Which bacteria are utilized in gobar gas plant? [RPMT 2008]

(1) Methanogens (2) Nitrifying bacteria

(3) Ammonifying bacteria (4) Denitrifying bacteria

27. During anaerobic digestion of organic waste, such as in producing biogas, which one of the following is left undergraded?

(1) Hemicellulose (2) Cellulose [AIPMT 2007]

(3) Lipids (4) Lignin

28. Azolla is used as a biofertilizer because it

(1) Multiplies very fast to produce massive biomass [Punjab PMET 2006]

(2) Has association of nitrogen fixing Rhizobium

(3) Has association of nitrogen fixing cyanobacteria

(4) Has association of mycorrhiza

29. Which is a bioinsecticide?

(1) Cactoblastis cactorum (2) Anabaena [DUMET 2006]

(3) Bacillus thuringiensis (4) Rhizobium

30. Match the following and choose the correct combination from the given option.

Column – I Column – II

(1) Anabaena (1) Bioherbicide

(2) Nicotine (2) Insect hormones

(3) Phytophthora palmivora (3) Natural insecticide

(4) Pheromones (4) Biofertilizer

A B C D [Kerala CEE 2005]

(1) 4 3 1 2

(2) 2 1 3 4

(3) 3 1 2 4

(4) 1 2 3 4

(e) 3 2 4 1

31. Biogas is pathogen free because [MHT CET 2005]

(1) Anaerobic digestion removes pathogens and bacteria

(2) It is toxic to pathogens

(3) During decomposition, it produces antibiotics

(4) Cattle dung is pathogen free

32. Bacterial fertilizer is

(1) Anabaena (2) Nostoc [MHT CET 2004]

(3) Rhizobium (4) Phycomyces

33. Insecticide obtained from neem plant is [MHT CET 2004]



(1) Pyrethrin (2) Pyrethroid (3) Thiocarbamate (4) Azadirachtin

34. Insecticides usually act upon

(1) Digestive system (2) Nervous system [J & K CET 2004]

(3) Circulatory system (4) Muscular system

35. From which one of the following plants, the insecticide pyrethrum is prepared?

(1) Vetivera (2) Cymbopogon [UPCPMT 2003]

(3) Chrysanthemum (4) Tephrosia

36. IPM (Integrated Pest Management) involves

(1) Tissue culture (2) Biological control [BCECE 2003]

(3) Biofertilizers (4) Confusion technique

37. In which one of the following processes CO2 is not released ? (AIPMT 2014)

(1) Alcoholic fermentation (2) Lactate fermentation

(3) Aerobic respiration in plants (4) Aerobic respiration in animals

38. The initial step in the digestion of milk in humans is carried out by? (AIPMT 2014)

(1) Rennin (2) Pepsin (3) Lipase (4) Trypsin

39. What gases are produced in anaerobic sludge digesters? (AIPMT 2014)

(1) Methane, Hydrogen Sulphide and O2

(2) Hydrogen Sulphide and CO2

(3) Methane and CO2 only

(4) Methane, Hydrogen Sulphide and CO2

40. High value of BOD (Biochemical Oxygen Demand) indicates that: (AIPMT 2015)

(1) water is highly polluted

(2) water is less polluted

(3) consumption of organic matter in the water is higher by the microbes

(4) water is pure

41. Match the following list of microbes and their importance (RE-AIPMT 2015)

(1) Sacharomyces cerevisiae (i) Production of immunosuppressive agents

(2) Monascus purpureus (ii) Ripening of Swiss cheese

(3) Trichoderma polysporum (iii) Commercial production of ethanol

(4) Propionibacterim sharmanii (iv) Production of blood-cholesterol lowering agents

(1) (2) (3) (4)

(1) (iii) (i) (iv) (ii)

(2) (iii) (iv) (i) (ii)

(3) (iv) (iii) (ii) (i)

(4) (iv) (ii) (i) (iii)

42. Which of the following is wrongly matched in the given table? (NEET-UG PHASE I 2016)

Microbe Product Application

(1) Clostridium butylicum Lipase removal of oil stains

(2) Trichoderma polysporum Cyclosporin A Immunosuppressive drug



(3) Monascus purpureus Statins lowering of blood cholesterol

(4) Streptococcus Streptokinase removal of clot from blood vessel

43. Match Column–I with Column–II AND select the correct option using the codes given below:

(NEET-UG PHASE II 2016)

Column I Column II

(1) Citric acid (i) Trichodenna

(2) Cyclosporin A (ii) Clostridium

(3) Statins (iii) Asperqillus

(4) Butyric acid (iv) Monascus

a b c d

(1) (iii) (i) (ii) (iv)

(2) (iii) (i) (iv) (ii)

(3) (i) (iv) (ii) (iii)

(4) (iii) (iv) (i) (ii)

44. Biochemical Oxygen Demand (BOD) may not be a good index for pollution for water bodies

receiving effluents from _____. (NEET-UG PHASE II 2016)

(1) domestic sewage (2) dairy industry

(3) petroleum industry (4) sugar industry

45. Which of the following in sewage treatment removes suspended solids? (NEET 2017)

(1) Tertiary treatment (2) Secondary treatment

(3) Primary treatment (4) Sludge treatment

46. Which of the following CORRECTLY matched for the product produced by them?(NEET 2017)

(1) Acetobacter aceti : Antibiotics (2) Methanobacterium : Lactic acid

(3) Penicillium notatum : Acetic acid (4) Sacchromyces cerevisiae : Ethanol

————



EXERCISE (KEY) LEVEL-I (CLASS WORK)

1. (1)

2. (3)

3. (1)

4. (2)

5. (3)

6. (4)

7. (1)

8. (2)

9. (3)

10. (1)

11. (2)

12. (1)

13. (2)

14. (3)

15. (4)

16. (2)

17. (3)

18. (4)

19. (2)

20. (3)

21. (4)

22. (4)

23. (3)

24. (2)

25. (2)

LEVEL-II (CLASS WORK)

1. (2)

2. (4)

3. (1)

4. (3)

5. (1)

6. (2)

7. (1)

8. (3)

9. (4)

10. (1)

11. (4)

12. (3)

13. (1)

14. (4)

15. (2)

16. (4)

17. (1)

18. (2)

19. (2)

20. (4)

21. (4)

22. (3)

23. (3)

24. (1)

25. (3)


1. (3)

2. (2)

3. (4)

4. (1)

5. (2)

6. (3)

7. (1)

8. (3)

9. (2)

10. (1)

11. (2)


1. (2)

2. (2)

3. (4)

4. (3)

5. (1)

6. (4)

7. (1)

8. (4)

9. (1)

10. (4)

11. (4)

12. (4)

13. (2)

14. (4)

15. (3)

16. (3)

17. (2)

18. (3)

19. (4)

20. (2)

21. (1)

22. (1)

23. (3)

24. (1)

25. (3)

26. (1)

27. (4)

28. (3)

29. (3)

30. (1)

31. (1)

32. (3)

33. (4)

34. (2)

35. (3)

36. (2)

37. (2)

38. (1)

39. (4)

40. (1)

41. (b

42. (1)

43. (2)

44. (3)

45. (3)

46. (4)

INDEX

Topic Name Page No.


Exercise 44-54

Level-I 44-45

Level-II 46-48



Answer 55-55


What is plant breeding?

Different activities in plant breeding

Common methods of crop improvement

Process of introduction

Quarantine

Hybridisation

Types of hybridisation

Inbreeding depression

Polyploid breeding

Autoallopolyploidy

Mutation breeding

Breeding for nutritional quality

Single cell proteins (scp)

New crops

Plant tissue culture and biotechnology

Proper nutrients medium

Types of cultures

Applications

STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION

Strategies for Enhancement in Food Production Rg.-Bot. XII-19-21


Traditional farming can only yield a limited biomass, as food for humans and animals. Better

management practices and increase in acreage can increase yield, but only to a limited extent. Plant

breeding as a technology has helped increase yields to a very large extent.

In India Green Revolution which was responsible for our country to not merely meet the national

requirements in food production but also helped us even to export. Green revolution was dependent to

a large extent on plant breeding techniques for development of high-yielding and disease resistant

varieties in wheat, rice, maize, etc.

What is Plant Breeding?

Plant breeding is the purposeful manipulation of plant species in order to create desired plant types

that are better suited for cultivation, give better yields and are disease resistant.

Conventional plant breeding has been practiced for thousands of years, since the beginning of human

civilisation; recorded evidence of plant breeding dates back to 9,000-11,000 years ago. Many present-

day crops are the result of domestication in ancient times. Today, all our major food crops are derived

from domesticated varieties.

Classical plant breeding involves crossing or hybridisation of pure lines, followed by artificial

selection to produce plants with desirable traits of higher yield, nutrition and resistance to diseases.

With advancements in genetics, molecular biology and tissue culture, plant breeding is now

increasingly being carried out by using molecular genetic tools.

If we were to list the traits or characters that the breeders have tried to incorporate into crop plants, at

first we would list the increased crop yield and improved quality. Increased tolerance to environmental

stresses (salinity, extreme temperatures, drought), resistance to pathogens (viruses, fungi and bacteria)

and increased tolerance to insect pests would be on our list too.

Plant breeding programmes are carried out in a systematic way worldwide–in government institutions

and commercial companies. The main steps in breeding a new genetic variety of a crop are –

(i) Collection of variability: Genetic variability is the root of any breeding programme. In many

crops pre-existing genetic variability is available from wild relatives of the crop. Collection

and preservation of all the different wild varieties, species and relatives of the cultivated

species (followed by their evaluation for their characteristics) is a pre-requisite for effective

exploitation of natural genes available in the populations. The entire collection (of

plants/seeds) having all the diverse alleles for all genes in a given crop is called germplasm

collection.

(ii) Evaluation and selection of parents: The germplasm is evaluated so as to identify plants with

desirable combination of characters. The selected plants are multiplied and used in the process

of hybridisation. Purelines are created wherever desirable and possible.

(iii) Cross hybridisation among the selected parents: The desired characters have very often to be

combined from two different plants (parents), for example high protein quality of one parent

may need to be combined with disease resistance from another parent. This is possible by cross

hybridising the two parents to produce hybrids that genetically combine the desired characters

in one plant. This is a very time-consuming and tedious process since the pollen grains from

the desirable plant chosen as male parent have to be collected and placed on the stigma of the

flowers selected as female parent. Also, it is not necessary that the hybrids do combine the

desirable characters; usually only one in few hundred to a thousand crosses shows the desirable

combination.

STRATEGIES FOR ENHANCEMENT IN FOOD PRODUCTION



(iv) Selection and testing of superior recombinants: This step consists of selecting, among the

progeny of the hybrids, those plants that have the desired character combination. The selection

process is crucial to the success of the breeding objective and requires careful scientific

evaluation of the progeny. This step yields plants that are superior to both of the parents (very

often more than one superior progeny plant may become available). These are self-pollinated

for several generations till they reach a state of uniformity, so that the characters will not

segregate in the progeny.

(v) Testing, release and commercialisation of new cultivars: The newly selected lines are

evaluated for their yield and other agronomic traits of quality, disease resistance, etc. This

evaluation is done by growing these in the research fields and recording their performance by

testing the materials in farmer's fields, for atleast three growing seasons at several locations in

the country, representing all the agroclimatic zones where the crop is usually grown. The

material is evaluated in comparison to the best available local crop cultivar – a check or

reference cultivar.

The phase of mid-1960s when several high yielding varieties of wheat and rice were developed,

is often referred to as the green revolution.

• N.E. Borlaug - Father of Green Revolution

• Dr. M.S. Swaminathan - Father of Green Revolution in India.

India is mainly an agricultural country. Agriculture accounts for approximately 33 per cent of

India’s GDP and employs nearly 62 per cent of the population. After India’s independence, one

of the main challenges facing the country was that of producing enough food for the increasing

population. As only limited land is fit for cultivation, India has to strive to increase yields per

unit area from existing farm land. The development of several high yielding varieties of wheat

and rice in the mid-1960s, as a result of various plant breeding techniques led to dramatic

increase in food production in our country. This phase is often referred to as the Green

Revolution. Figure represents some Indian hybrid crops of high yielding varieties.

(a)

(b)

(c)

Some Indian hybrid crops: (a) Maize; (b) Wheat; (c) Garden peas



Different Activities in Plant Breeding

Common Methods of Crop Improvement

1. Plant introduction and Acclimatization

It is the process of introducing plants with specific characters from their area of origin to a new area.

It is of two types:

IC (Indigenous collection): When introduction is made from same country. e.g. Sonalika (wheat), IR-

8, IR-24 (Rice)

EC (Exotic collection): When introduction is made from foreign country. e.g. Taichung Native-1

(Rice) Sonara 63, Sonara 64, Lerma Roja 64-A (wheat)

Introduced plant may be used directly for cultivation (primary introduction) or may be used after

subjecting to selection/hybridisation (secondary introduction).

Wheat:

A dwarfing gene Norin-10 was reported in Japan. Norman E. Borlaug at international centre of wheat

and maize improvement in Mexico produced semi dwarf wheat, popularly known as Mexican wheat.

These had high yield, resistance for lodging and common pathogens and pests and smaller growth

period. In 1963, several varieties such as Sonalika and Kalyan sona, which were high yielding and

disease resistant, were introduced all over the wheat growing belt of India. These had been obtained by

hybridization between mexican and indian varieties. By mutational breeding of varieties like Lerma

Rojo 64 A and Sonora 64, varieties like Pusa Lerma and Sharbati Sonora were obtained. During the

period 1960 to 2000, wheat production increased from 11 million tonnes to 75 million tonnes.

Rice:

During the period 1960 to 2000, rice production went up from 35 million tonnes to 89.5 million

tonnes. A dwarfing gene of rice dee-geo-woo-gen, was reported in Taiwan and was used to produce

variety Taichung Native -1. The gene was used by IRRI (International Rice Research Institute),

Philippines to develop variety IR-8(miracle rice). The derivatives were introduced in 1966. IR36 was

developed by Dr. Khush and his team at IRRI and was widely used. Later better yielding semi dwarf

varieties Jaya and Ratna were developed in India.

G.S. Khush: Father of Miracle Rice, IR-36 (Developed by crossing 13 varieties of rice with Indian

rice variety Oryza nivara found in Kerala).



Sugar Cane: Saccharum barberi was originally grown in north India, but had poor sugar content and

yield. Tropical canes grown in south India Saccharum officinarum had thicker stems and higher sugar

content but did not grow well in north India. These two species were successfully crossed to get sugar

cane varieties combining the desirable qualities of high yield, thick stems, high sugar and ability to

grow in the sugarcane areas of north India.

Millets:

Hybrid maize, jowar and bajra have been successfully developed in India. Hybrid breeding have led to

the development of several high yielding varieties resistant to water stress. Lysine rich varieties like

Shakti, Rattan and Protina have been developed in India.

Process of Introduction

Collection of germplasm

Plant Inspection / Quarantine

Catalogueing

Evaluation

Acclimatization in different agroclimatic zones (There are 15 agroclimatic zones in India.)

Multiplication and release of variety to farmers

• Failure of proper inspection/quarantine sometimes results in introduction of some diseases along

with introduced material e.g. Coffee rust, Late blight of potato, Pea rust etc.

Acclimatization: Introduced plant must be adapted to new locality. The phenomenon is called

acclimatisation.

Since pre-historic periods: e.g. Apple, Walnut, Sesame, Mustard.

By Portuguese : Potato, Sweet Potato, Tobacco, Guava, Maize, Groundnut and Pine-apple.

Quarantine

Plant quarantine is meant for preventing introduction of exotic pests, weeds and diseases into the

country under DIP (Destructive Insects and Pests) Act 1914. Twenty six plant quarantine and

fumigation stations have been set up. Ten at international airports, nine at seaports, and seven at land

frontiers. The inspectors are trained at National Plant Protection Training Institute, Hyderabad.

Selection

It is picking up only those plants for reproduction which have desired qualities. It is called artificial

selection.

Selection preserves the favourable variations & eliminates the undesirable variations. It is the oldest

technique of crop improvement. Many crop plants are now unable to grow in wild. They have become

completely dependent on human beings for their survival e.g. Maize. Because of this Maize is often

called pampered corn. In many cases, even wild ancestry has become obscure. e.g. Cabbage, Maize

etc.

Selection is of three types:

1. Mass Selection : It consists of picking up seeds of a large number of phenotypically superior

plants & sowing them next season in a mass without any progeny testing. It eliminates undesirable

traits and increases the frequency of desirable traits. It is useful method in self pollinated as well as

cross pollinated plants.

Advantage: (i) It is the easiest method of selection.

(ii) It is the quickest method of selection.



Drawbacks: (i) The selection is not stable.

(ii) It neglects male plant and induces inbreeding depression.

(iii) Loss of superior heredity.

2. Pure line Selection: Used for developing wheat varieties - PV-18, Kalyan Sona, HUW-468,

and maize varieties - Vijaya and Ganga.

It is differential reproduction of only those plants where good characters have been brought in

homozygous state through self breeding over a few generations. The method is useful for bringing

about the maximum & permanent improvement in desired traits. Effect of environment is

eliminated. Progeny is also uniform.

Advantage : (i) It is stable and permanent selection.

Drawbacks : (i) It takes a lot of time & is useless in case of cross pollinated plants.

3. Clonal Selection : : Used for developing Kufri Safed potato, Bombay green Banana, Navel

Orange and Blood Red Sweet Orange. It is picking up plants with useful variations for

vegetative multiplication. Clonal selection is equally useful in maintaining superiority of

heterozygous, heteroploid or odd ploid individual.

Advantage: (i) The method gives instant success.

(ii) It is also stable selection.

Drawbacks: (i) An infection spreads to all progeny.

(ii) It is only applicable to vegetatively propagated plants.

(iii) New traits cannot be introduced.

Hybridisation

It is crossing of two or more types of plants for bringing their traits together in the progeny.

Hybridisation brings about useful genetic/heritable variations of two or more lines together.

Line: It is a group of individuals having a common lineage and similar genotype.

Parents: The individual lines used in hybridisation are called parents.

It takes a lot of time. e.g. 12 years for wheat variety HUW-468. Hybridisation may involve a single

cross (two plants) or multiple cross (more than two plants). Wheat variety C-306 (Dry land) was

developed through multiple cross.

High yielding rice variety ADT-37 is interspecific hybrid between Oryza japonica and O. indica. All

the present day cultivated sugarcane varieties are interspecific hybrids. The various steps involved in

hybridisation are as follows :

1. Selection of Parents: Plants with desirable characters are selected as parents.

2. Selfing: The plant selected as parents are allowed to undergo self breeding to bring about

homozygosity of desired traits. In each generation some defective plants appear due to defective

alleles becoming homozygous. They are discarded.

3. Emasculation : It is removal of male parts or anthers from the future female parent plants in the

young state so as to avoid chances of contamination from their own pollen. In case of unisexual

plants, the male plants are not allowed to grow near the female plants. For large intersexual

flowers, anthers are easily removed by means of scalpel or scissors.

Artificial male sterility : It can be induced in certain cases by:

(i) Dipping inflorescence of female parent in hot water at 50°C for ten minutes e.g. Sorghum

(ii) Inverting a wide test tube having moist paper over the inflorescence when anthers come out.

e.g. Ragi (Millet).



(iii)Spraying inflorescence with maleic hydrazide (MH), 2, 4 - D (50 ppm) or NAA.

Natural male sterility : It is present in certain lineages due to presence of plasmagenes and recessive

nuclear genes. e.g. sunflower, tomato, cucumber, maize, carrot, barley. It is not present in wheat, rice,

chickpea & all the leguminous plants.

4. Bagging: Flowers of both male and female parents are kept covered with paper plastic or

polythene bags from the very beginning, just to avoid unwanted pollen landing.

5. Crossing or Artificial Pollination

6. Creation of Variability: This gives rise to F1 generation. An F2 generation is also got so as to

bring out various allelic combinations.

7. Back Crossing: After backcrossing the plants are allowed to self breed for 2-3 generations for

achieving genetic variability.

8. Selection:

(i) Selection in Self Pollinated Plants : The degree of cross pollination is less than 5%. The best

one is used as a new variety. It is a pure line and is not affected by repeated selfing. e.g. HUW-

468 wheat. Variation appearing later in such a pure line are due to environment, an occasional

mutation may be an exception.

(ii) Selection in Cross Pollinated Plants : The selected plants are not allowed to self breed but

crossbred so that heterozygosity is also maintained. Selection can be continued in a few

successive generations.

9. Evaluation and Release of Varieties: Evaluations are usually carried out by Indian Council of

Agricultural Research (ICAR), New Delhi. The varieties produced by many breeders are evaluated

simultaneously in different agroclimatic zones (on basis of climate and soil, maximum 8,

minimum 2 depending upon crop) for three consecutive years.

A variety release community goes through the details, accepts the proposal and paves the way for

its naming and release as new variety. The same is notified by Government of India.

10. Multiplication of Improved Seed: The seed packet must carry the stamp of National seed

corporation, date of test, purity of seed (99%), absence of other crop/weed seed (0%), inert matter

(1%) and duration and validity of the certificate and special features of the quality. Such a seed is

also called certified seed. National Seed Corporation 1965 (NSC) is responsible for maintaining

the quality of seed.

TYPES OF HYBRIDISATION

It is of three types

Inbreeding Depression

Inbreeding is mating of individuals closely related by ancestry. Inbreeding is used in developing pure

lines or homozygous lines. Selfing or self pollination is the extreme form of inbreeding. Loss of vigour

and appearance of a number of defective traits associated with inbreeding is called inbreeding

depression. It is due to development of homozygosity in case of recessive alleles, most of which are



harmful. Normally, they remain unexpressed because cross pollination makes the plants highly

heterozygous.

Hybrid Vigour or Heterosis

The superiority of the hybrid (F1 plant) over

either of its parents in one or more traits is called

hybrid vigour or heterosis. The term was coined

by Shull (1912) though heterosis was first

studied by Kolreuter (1763) followed by

Darwin (1876). For hybrid vigour, the parents

should have complementary genes.

The increased yield varies from 25-300%. At one time hybrid Maize was grown in large tracts all over

the world. It is now replaced by composite varieties. The reason is that heterosis disappears on

inbreeding & declines in others. It is profitable in vegetatively propagated plants. e.g. Mango, Apple,

Potato, Sugarcane.

Polyploid Breeding

Polyploid is an individual having more than diploid or more than two sets of chromosomes. The

phenomenon of having one or more genomes in addition to the normal number for the species is called

polyploidy. Many of modern day crops such as wheat, rice, sugarcane, cotton are natural polyploids. It

is induced artificially by colchicine (spindle poison) and granosan. Colchicine is an alkaloid. It

prevents spindle formation but otherwise allows replication of chromosomes. This results into the

formation of polyploid nucleus.

Polyploidy is of two types

(i) Primary polyploidy: It is the increase in the number of complete chromosome set as present in

the original species.

(ii) Secondary polyploidy: It is the increase in chromosome complement of an aneuploid. e.g. Apple,

Pear, Rice.

On the basis of genomes involved, polyploidy is of three types:

(i) Autopolyploidy: Autopolyploidy is produced spontaneously in nature in low frequency. It can be

induced in relatively high frequencies by colchicine. It is the increase in number of genome.

Autotetraploid (AAAA) is formed by failure of meiosis with the help of mitotic poison like

colchicine. Autotriploid (AAA) is formed by cross between tetraploid & diploid. Failure of

meiosis during formation of gametes (or spores) forms diploid egg or diploid sperm. Fusion of

diploid gamete with diploid one forms tetraploid individual while fusion of diploid gamete with

haploid one forms triploid individual. All autopolyploids show gigas effect, that is larger size,

more juice, more sugar, more grains etc. Triploids are sexually sterile. An autotriploid variety of

tea has also been developed in India. Autotetraploids are sexually fertile but have relatively lower

fertility than the diploid forms. e.g. Potato, Groundnut, Coffee etc.

(ii) Allopolyploidy: It is also called interspecific polyploidy because increase in number of genomes

or chromosome sets is due to pooling from individuals of two or more species caused by

hybridisation followed by chromosome doubling. e.g. AABB, AABBCC. The most common types

are allotetraploids or amphidiploids (AABB). Allopolyploidy immediately forms new species.

Some common examples are Durum wheat (AABB), Bread Wheat (AABBDD), New World

Long Stapled Cotton (AADD) Brassica napus (AACC), Brassica juncea (AABB) & Tobacco

(Nicotiana tobaccum, AABB). Raphanobrassica was the first artificial allotetraploid (AABB)

prepared by Karpechenko (1972) by first crossing Raphanus sativum (Radish) with Brassica

oleracea (Cabbage) followed by chromosome doubling. Triticale (Tritisecale) is an allopolyploid

between wheat & Rye. Triticale octaploid (AABBDDEE) is an allopolyploid between hexaploid



bread wheat (Triticum aestivum, AABBDD) and Rye (Secale cereale, EE) which was developed

by Muntzing (1966). Triticale hexaploid (AABBEE) is a similar allopolyploid between Durum

wheat (Triticum durum/T. turgidum AABB) and Rye (Secale cereale, EE).



Origin of Triticale (Man-Made Crop):

Autoallopolyploidy

It is pooling of chromosome sets from two species, one with diploid and the other with more than

diploid states. e.g. Helianthus tuberosum (AAAABB).

Plant Breeding for Disease Resistance:

A wide range of fungal, bacterial and viral pathogens, affects the yield of cultivated crop species,

especially in tropical climates. Crop losses can often be significant, upto 20-30 per cent, or sometimes

even total. The conventional method of breeding for disease resistance is that of hybridisation and

selection. Some crop varieties bred by hybridisation and selection, for disease resistance to fungi,

bacteria and viral diseases are released.

This also helps reduce the dependence on use of fungicides and bacteriocides. Resistance of the host

plant is the ability to prevent the pathogen from causing disease and is determined by the genetic

constitution of the host plant. Before breeding is undertaken, it is important to know about the

causative organism and the mode of transmission. Some of the diseases caused by fungi are rusts, e.g.,

brown rust of wheat, red rot of sugarcane and late blight of potato; by bacteria – black rot of crucifers;

and by viruses – tobacco mosaic, turnip mosaic, etc.

Methods of breeding for disease resistance: Breeding is carried out by the conventional breeding

techniques (described earlier) or by mutation breeding. The conventional method of breeding for

disease resistance is that of hybridisation and selection. It’s steps are essentially identical to those for

breeding for any other agronomic characters such as high yield. The various sequential steps are :

screening germplasm for resistance sources, hybridisation of selected parents, selection and evaluation

of the hybrids and testing and release of new varieties.

Some crop varieties bred by hybridisation and selection, for disease resistance to fungi, bacteria and

viral diseases are :

Table :

Crop Variety Resistance to disease

Wheat Himgiri Leaf and stripe rust, hill bunt

Brassica Pusa swarnim (Karan rai) White rust

Cauliflower Pusa Shubhra, Pusa Snowball K-1 Black rot and Curl blight black rot

Cowpea Pusa Komal Bacterial blight

Chilli Pusa Sadabahar Chilly mosaic virus, Tobacco

mosaic virus and Leaf curl



Conventional breeding is often constrained by the availability of limited number of disease resistance

genes that are present and identified in various crop varieties or wild relatives. Inducing mutations in

plants through diverse means and then screening the plant materials for resistance sometimes leads to

desirable genes being identified. Plants having these desirable characters can then be either multiplied

directly or can be used in breeding. Other breeding methods that are used are selection amongst

somaclonal variants and genetic engineering.

Mutation Breeding

Mutation is the process by which genetic variations are created through changes in the base sequence

within genes resulting in the creation of a new character or trait not found in the parental type. It is

possible to induce mutations artificially through use of chemicals or radiations (like gamma

radiations), and selecting and using the plants that have the desirable character as a source in breeding

– this process is called mutation breeding. In mung bean, resistance to yellow mosaic virus and

powdery mildew were induced by mutations.

Several wild relatives of different cultivated species of plants have been shown to have certain

resistant characters but have very low yield. Hence, there is a need to introduce the resistant genes into

the high-yielding cultivated varieties. Resistance to yellow mosaic virus in bhindi (Abelmoschus

esculentus) was transferred from a wild species and resulted in a new variety of A. esculentus called

Parbhani kranti.

All the above examples involve sources of resistance genes that are in the same crop species, which

has to be bred for disease resistance, or in a related wild species. Transfer of resistance genes is

achieved by sexual hybridisation between the target and the source plant followed by selection.

Mutations are new stable inheritable discontinuous variations which appear suddenly due to change in

nucleotides representing cistrons or genes. It is possible to induce mutations artificially through use of

chemical or radiations (like gamma radiations). Gamma ray treatment of Pelita -1 rice in Indonesia has

produced high yielding variety called Atomita-2 which is also resistant to brown plant hopper. Reimei

is another high yielding variety produced through gamma radiation. Incorporation of useful mutations

in developing improved varieties is called mutation breeding.

Plant breeding for developing resistance to insect pests

Breeding method for insect pest resistance involve the same steps as those for any other

agronomic trait. Another major cause for large scale destruction of crop plant and crop produce

is insect and pest infestation. Insect resistance in host crop plants may be due to morphological,

biochemical or physiological characteristics. e.g.

Resistance to jassids in cotton and several leaf beetles in wheat is due to hairy leaves.

Solid stem of wheat also show non preference by the stem sawfly and smooth leaved, and nectar

less cotton varieties do not attract bollworms.

High aspartic acid, low nitrogen and sugar content in maize leads to resistance to maize stem

borers. Some released crop varieties bred by hybridisation and selection for insect pest resistance

are:

Crop Variety Insect Pests

Brassica (rapeseed

mustard) Pusa Gaurav Aphids

Flat bean Pusa Sem 2

Pusa Sem 3 Jassids, aphids and fruit borer

Okra (Bhindi) Pusa Sawani

Pusa A-4 Shoot and Fruit borer



Breeding for Nutritional Quality

More than 840 million people in the world do not have adequate food to meet their daily food and

nutritional requirements. A far greater number– three billion people – suffer from micronutrient,

protein and vitamin deficiencies or ‘hidden hunger’ because they cannot afford to buy enough fruits,

vegetables, legumes, fish and meat. Diets lacking essential micronutrients – particularly iron, vitamin

A, iodine and zinc – increase the risk for disease, reduce lifespan and reduce mental abilities.

Biofortification – breeding crops with higher levels of vitamins and minerals, or higher protein and

healthier fats – is the most practical means to improve public health.

Breeding for improved nutritional quality is undertaken with the objectives of improving :

(i) Protein content and quality;

(ii) Oil content and quality;

(iii) Vitamin content; and

(iv) Micronutrient and mineral content.

In 2000, maize hybrids that had twice the amount of the amino acids, lysine and tryptophan,

compared to existing maize hybrids were developed.

Wheat variety, Atlas 66, having a high protein content, has been used as a donor for improving

cultivated wheat.

It has been possible to develop an iron-fortified rice variety containing over five times as much

iron as in commonly consumed varieties.

The Indian Agricultural Research Institute, New Delhi has also released several vegetable crops

that are rich in vitamins and minerals, e.g.,

Vitamin A enriched carrots, spinach, pumpkin;

Vitamin C enriched bitter gourd, bathua, mustard, tomato;

Iron and calcium enriched spinach and bathua; and

Protein enriched beans – broad, lablab, French and garden peas.

SINGLE CELL PROTEIN (SCP) Conventional agricultural production of cereals, pulses, vegetables, fruits, etc., may not be able

to meet the demand of food at the rate at which human and animal population is increasing.

The shift from grain to meat diets also creates more demand for cereals as it takes 3-10 Kg of

grain to produce 1 Kg of meat by animal farming. More than 25 per cent of human population

is suffering from hunger and malnutrition. One of the alternate sources of proteins for animal

and human nutrition is Single Cell Protein (SCP).

Microbes are being grown on an industrial scale as source of good protein. Microbes like

Spirulina can be grown easily on materials like waste water from potato processing plants

(containing starch), straw, molasses, animal manure and even sewage, to produce large

quantities and can serve as food rich in protein, minerals, fats, carbohydrate and vitamins.

Incidentally such utilisation also reduces environmental pollution.

It has been calculated that a 250 Kg cow produces 200 g of protein per day. In the same period,

250g of a micro-organism like Methylophilus methylotrophus, because of its high rate of

biomass production and growth, can be expected to produce 25 tonnes of protein. The fact that

mushrooms are eaten by many people and large scale mushroom culture is a growing industry

makes it believable that microbes too would become acceptable as food.

SCP is rich in high quality protein and poor in fats. Commercial production of SCP is mostly

based on some fungi, e.g. Fusarium graminearum.



New Crops:

Winged Bean (=Goa Bean, Psophocarpus tetragonolobus) : It is a nitrogen fixing herbaceous vine

found in tropical Asia which can reach a height of 3m when provided with support. The plant has

tuberous roots and long pods with four prominent wings. All parts of the plants are edible and rich in

protein.

Jojoba (=Hohoba, Simnondsia chinensis) : It is a drought resistant shrubby dioecious plant which

grows naturally in the mexican deserts. The plants can tolerate poor soil and low moisture conditions.

Therefore, it can be economically exploited in arid areas.

Jojoba oil can penetrate outer layers of human skin. It can therefore, be an important ingredient of

cosmetics and external medicines. Like sperm whale oil, jojoba oil has the ability to function as high

performance lubricant for fine machinery.

Guayule (= Wayule, Parthenium argentatum) : It is a small, brittle shrub found growing wild in the

marginal and poor desert soils of South-Western U.S.A. and adjacent Mexico. Latex of Guayule

produces natural rubber similar to that of para or hevea rubber. Since the requirement of natural

rubber has increased with the introduction of radial tyres, Guayule becomes a potential source for the

same. The shrubs are harvested along with roots when the plants are seven years old.

Leucaena (Subabul, Leucaena leucocephala) : A fast growing (upto 8 m/yr) leguminous shrub or

small tree, originally belonging to central America, is naturalised in India. It enriches the soil with

nitrogenous chemicals. Therefore, the plant is capable of growing on poor, marginal soils. It is planted

on roadsides, as wind breaks. The leaves being rich in nitrogenous compounds are a good green

manure.

PLANT TISSUE CULTURE AND BIOTECHNOLOGY

Discovery

• Tissue culture technique was first thought of by Haberlandt (1902) and Hanning.

• First successful attempt was made by White (1932) in case of Tomato root. He also developed the

technique of sub culturing.

• Skoog and Miller (1957) found that growth and morphogenesis were controlled by hormones,

auxin (root formation) and cytokinin (shoot formation).

• Formation of embryoids or somatic embryos was discovered by Steward (1963), Helperin and

Wetherell (1964).

• Concept of cellular totipotency was first given by Haberlandt (1902) but was proved by Steward

(1965).

• Guha and Maheswari developed haploid or pollen culture technique for obtaining haploid

embryoids and perfectly homozygous plants.

Plant tissue culture is the technique of in vitro maintaining and growing cells, tissues, organs etc.

and their differentiation on artificial nutrient medium under aseptic conditions inside suitable

containers (e.g. test tube), under controlled environmental conditions.

This is one of the latest and most promising methods of crop improvement in such plant, where

other conventional methods of breeding fail.

Tissue culture technique is based on totipotent nature of plant cell.

Plant tissue culture are often classified according to the type of in vitro growth (e.g. callus and

suspension culture), or the explant used for culture initiation (e.g. embryo culture, anther culture

etc.)

Explant : Plant part that is excised from its original location and used in initiating a culture. It may

be shoot tip, root tip, shoot bud, anther, embryo, ovule etc. Normally undifferentiated and

meristematic cells of plants are used as explant.

Surface sterilization : The process by which explants are treated with specific antimicrobial

chemical like H2O2, sodium hypochloride, Bromine water, C2H5OH etc.



Sterlization : The vessel, media and instruments are also suitably treated with steam, dry heat or

alcohol or subjected to alteration to make them free from microbes.

Proper Nutrients Medium

• It may be liquid, semi-solid or solid. The semi-solid and solid media are prepared by heating the

nutrient solution with less than 1% agar or gelatin. The nutrient solution contains 2-4% sugar,

vitamins, minerals (basal medium) and growth regulators. The growth regulators can be replaced

by organic complexes like coconut milk, banana pulp or yeast extract. The most extensively used

medium is MS medium developed by Murashige and Sloog in 1962. An optimum pH of 5.7 is

also important.

• Aseptic Conditions : All types of apparatus, including containers, forceps, needles and the

nutrient medium are sterilised in an autoclave (temperature over 120°C) for 15-30 minutes.

Inoculation chamber is disinfected with ultraviolet rays.

• Aeration : In liquid medium culture, air is provided through filter paper bridge, shaking or

passing of sterilised air.

Types of Cultures

(1) Callus and suspension culture

(2) Meristem culture

(3) Embryo culture

(4) Anther culture

(5) Protoplast culture

(6) Plant tissue cultures are often classified according to the type of in vitro growth viz., callus

and suspension cultures or the explant used for culture initiation e.g., embryo culture, anther

culture etc.

(7) Based upon the part of organism there are different types of cultures represented below as

flow charts.

A flow-chart showing the various types of plant tissue culture and recovery of complete plants from them : (a)

callus and suspension cultures, (b) anther, protoplast, embryo and shoot tips



(1) Callus And Suspension Culture

Depending upon the type of explant, tissue culture is called shoot tip culture, multiple shoot

culture, anther/ haploid culture, embryo culture, embryoid culture etc.

On the basis of in vitro growth, plant tissue culture are of two types, callus and suspension

cultures.

Callus is irregular, unorganised and undifferentiated mass of actively dividing cells. Darkness and

solid medium gelled by agar, stimulates callus formation. Both the growth regulators (2, 4-D and

BAP) are added. This stimulates cell division in explant. Callus is obtained within 2-3 weeks.

In suspension culture single cells or small groups of cells are suspended in constantly agitated

(100-250 rpm) liquid medium having 2, 4-D. In suspension culture growth is faster as compared to

callus culture. Agitation helps in aeration of culture, mixing of medium and breaking of cell

aggregates into single or few celled, groups. With the passage of time

- cell/tissue biomass increases,

- level of nutrients and growth regulators fall,

- volume of medium declines and there is accumulation and wastes.

Cultures are regularly divided and transferred to containers having fresh media. The process is

called subculturing. Callus and suspension cultures are used for increasing cell biomass for

biochemical extractions, quick vegetative propagation (through regeneration of plantlets),

induction of mutations, development of transgenic plant and isolation of protoplasts.

Callus Culture Suspension Culture

1. In this culture, cell division in explant

forms a callus. Callus is an irregular

unorganised and undifferentiated mass of

actively dividing cells.

1. It consists of single cells and small groups of

cells suspended in liquid medium.

2. The culture is maintained on agar

medium

2. The culture is maintained in liquid medium

3. The medium contains growth regulator

the auxin such as 2, 4 -D and cytokinin

like BAP.

3. The medium contains growth regulator the auxin

such as 2, 4-D only

4. Callus is obtained within 2 - 3 weeks. 4. Suspension culture grows much faster than callus

culture.

5. It does not need to be agitated. 5. It must be constantly agitated at 100-250 rpm

(revolutions per minute).

Formation of Plantlets

Formation of organised structures like shoot, somatic embryo or plantlet from callus/suspension and

other forms of tissue culture is called regeneration. Plants are obtained by two methods:-



(i) Shoot Regeneration - Callus culture

provided with cytokinin (e.g. BAP)

differentiate into shoots. As the shoots

become 2-3 cm, they are excised and taken to

another culture medium having auxins like

NAA (Napthalene acetic acid). Roots

develop at the lower ends of shoots to form

plantlets.

(ii) Somatic Embryo Regeneration - It is the

process of forming somatic or nonzygotic

embryo like structures called embryoids.

Embryoids generally develop from callus

cells raised from immature embryo when

placed over culture medium having

ammonium, nitrogen and auxin like 2, 4-D.

> Mature somatic embryos germinate to

yield complete plantlets.

> The plantlets can be shifted from culture

medium to green house for undergoing

hardening process. In this process

plantlets are exposed to reduced light and

humidity for a suitable period of time.

This process is essential for plantlets as

they adjust themselves and can cope up

with unfavourable environmental

conditions, in future.

Fig : Schematic representation of subculturing

Applications

1. Rapid Clonal Propagation - Tissue culture is a technique to raise very large number of plants of

the same genotype within a span of a couple of months. The technique is used in rapid propagation

of superior and rare lines e.g. Oil Palm

2. Somaclonal Variations - They are stable variations which develop spontaneously in culture e.g. -

rust resistance and high temperature tolerance in wheat, resistance to Tungro virus and leaf ripper

in Rice, short duration sugarcane, increase shelf life in Tomato.

3. Transgenic Plants - Useful genes from other sources can be introduced in plant cell through

genetic engineering. They are called transgenes. Cells/organisms with transgenes are called

transgenic cells/organisms.

4. Induction and Selection of Mutations - The cells are washed and transferred to solid culture for

raising mutant plants. Useful mutants are selected for further breeding to induce tolerance to stress

like pollutants, toxins, salts, drought flooding etc. The surviving healthy cells are taken to solid

medium for raising resistant plants.

5. Resistance to weedicides - Weedicides are added to culture initially in very small concentration.

Dosage is increased in subsequent culture till the desired level of resistance is obtained. The

resistant cells are then regenerated to form plant.

Meristem Culture

The explants are shoot tips and nodal sections of 3rd and 4th nodes. They are raised in cytokinin (e.g.

BAP) rich medium. Cytokinin promotes formation of auxillary buds (it overcomes apical dominance).



Therefore, multiple shoots are formed. The technique is therefore also called multiple shoot culture.

For developing multiple shoots from shoot tips, salt and NAA are often added to culture medium. As

the shoots grow to a size of 2-3 cm, they are excised and transferred to medium rich in auxin for

induction of rooting. Meristem culture is carried out in Potato, etc. It is used in:

(i) Production of virus-free plants

(ii) Germplasm conservation

(iii) Production of transgenic plants

(iv) Rapid clonal multiplication

Micropropagation by stimulation of axillary buds to develop into shoots

Embryo Culture

It is the technique of taking out young/fragile/dominant embryos from developing seeds and their

growth on culture medium to form seedling and then young plants. Embryo culture has following

applications

• Embryo Rescue - It is taking out the fragile embryos from fertilised ovules of interspecific crosses

before their abortion and culturing them to form viable hybrid seedlings. e.g. Jute, Tomato, Bean.

• Orchids - Orchid seeds lack stored food. Embryo culture helps in developing seedlings from all

the seeds. The technique is also useful in clonal multiplication.

• Dormant Seeds - Inhibitors present in endosperm and other parts of seeds do not allow the

embryos to grow. It eliminates the action of inhibitors and dormancy.

• Rare Plants - The technique is useful in multiplication of some rare plants.

Anther Culture and Haploid Production

This technique was first used in India to produce haploid plants of Datura innoxia by Guha and

Maheshwari (1964). It is highly useful for immediate expression of mutations and quick formation of

pure lines. Very young unopened floral buds are first sterilised in clorox (common bleach) for 10-20

minutes. They are then opened to remove anthers. Anthers are introduced over culture medium within

4-6 weeks, each anther gives rise to either a number of haploid embryoids from its haploid pollen or a

haploid callus from which shoots regenerate. In haploids all mutations show their effect. Therefore,

they are useful for induction of mutations and mutation breeding. Normally they form sterile haploid

plants. Androgenic haploid plants have some variation which are called gametoclonal variation.



Gynogenic haploids are now possible by using unfertilised ovules. Haploid culture technique is also

used in reshuffling of alleles. For this two pure breeding plants are now allowed to hybridise and the

anthers of hybrid are used to develop haploids which are converted into homozygous diploids by

colchicine treatment. Superior lines are selected for further breeding.

(Production of homozygous lines using anther culture.

The two parents are shown to differ for only one gene i.e. AA and aa).

Protoplast Culture (Somatic Hybridisation)

Discovered by Cocking

The process of producing somatic hybrids is called somatic

hybridisation. First the cell wall of the plant cells are

removed by digestion with a combination of pectinase and

cellulase. The plant cells without cell wall are called

protoplasm. The protoplasts of the two plants are brought in

contact and made to fuse by means of electrofusion or

chemicals like polyethylene glycol (PEG) and sodium nitrate.

Substance which induce the fusion of protoplast are called

fusogen or fusogenic agent. The fusion of protoplasts not

only involves the fusion of their protoplasm but also their

nuclei. The fused protoplasts are allowed to grow on culture

medium. Somatic hybrids in plants were first obtained

between two species of Tobacco (Nicotiana glauca and

N.langsdorfit) by Carlson et.al. in 1972. Pomato is somatic

hybrid between Potato and Tomato that belong to two

different genera. The hybrid plant bears both fruits and tubers

of the two parents. It is useful in:

(a) Asexually reproducing plants.

(b) Possibility of development of new crop plants, e.g.

Pomato, Bromato (Brinjal and Tomato)

(c) Used for the production of useful allopolyploids.

(d) Genetic manipulations can be carried out more rapidly.

New genes can be introduced (e.g. male sterility,

herbicide resistance).



(c) Production of useful allopolyploids

(d) Transfer of cytoplasm.

• Somatic hybridisation is also called parasexual hybridisation since it does not involve meiosis

and syngamy.

• First somatic hybrids were obtained between two species of tobacco Nicotiana glauca and N.

langsdorfit by Carlson et. at.

Somatic hybridisation (a) Production of proplasts using combination of pectinase and cellulase

(b) protoplast fusion induced by PEG.

————



EXERCISE # LEVEL-I (CLASS WORK)

1. Which of the following methods is/are used in recovery of healthy plants from diseased plants?

(1) embryo culture (2) meristem culture

(3) suspension culture (4) anther culture

2. In shoot and root culture, excess of auxin in the medium will promote

(1) shoot culture (2) root culture

(3) both shoot and root culture (4) none of these

3. The colour of high yielding Mexican wheat was not liked by the Indians. It was originally red

grained. Their cultivation was adopted in India on large scale only when exposure to gamma

radiations converted to amber grained. Which of following methods of plant breeding has been

put into practice in the given case?

(1) polyploidy breeding (2) interspecific hybridization

(3) genetic engineering (4) mutation breeding

4. Green revolution in India was possible due to

(1) better irrigation, fertilizers and pesticide facilities

(2) exploitation of high yielding varieties

(3) intensive cultivation

(4) All of the above

5. Which of the following is/are the advantage(s) of micropropagation?

(1) it helps in rapid multiplication of plants

(2) it helps in production of somaclones

(3) it is an easy, safe and economical method for plant propagation

(4) all of the above

6. Which of the following methods of breeding increases the chance of homozygosity?

(1) inbreeding (2) out breeding

(3) out crossing (4) cross breeding

7. Improved varieties of wheat suitable for Indian climate have been developed by

(1) hybridization and mutation (2) mutation and cloning

(3) cloning and polyploidy (4) polyploidy and hybridization

8. Improved rice variety IR – 8 has been introduced in India from

(1) Taiwan (2) Japan

(3) Phillippines (4) Bangladesh

9. Amino acids present in improved varieties of maize are

(1) methionine and alanine (2) alanine and cysteine

(3) methionine and cysteine (4) lysine and tryptophan

10. Pure line breeds refer to

(1) homozygosity and independent assortment

(2) homozygosity only

(3) heterozygosity (4) heterozygosity and linkage

11. The most common sources of single cell protein are

(1) yeasts (2) bacteria

(3) other fungi (4) all of these

12. Culture of isolated microspores results in the formation of

(1) Microgametophyte (2) male gametes

(3) Haploid embryoids (4) Heterozygous embryoids

13. Haploids are considered better genetic stock because they

(1) Need only half of the total nutrients (2) Are best for cytological studies

(3) Grow better under all conditions

(4) Form homozygous individuals on diplodization



14. The plant part which is used in a culture is called

(1) Explant (2) Endplant

(3) Transplant (4) Callus

15. Germplasm also preserves rare genotype for

(1) Cultivation on large scale (2) Tracing the history of evolution

(3) Breeding and improvement (4) Chromosome study

16. Triticale is the first man made cereal crop. The combination of parents involve Triticum and

(1) Sorghum (2) Barley

(3) Saccharum (4) Rye

17. Autopolyploidy can be induced artificially by

(1) chloroform (2) Colchicine

(3) chloroquine (4) Colchine

18. Which one of the following is the common hexaploid bread wheat?

(1) Triticum aestivum (2) Triticum durum

(3) Triticum monococcum (4) Triticum turgidum

19. The application of induced mutations for crop improvement is called

(1) Mutation breeding (2) Apomixis

(3) Adventive embryony (4) Cloning

20. What was the source of first induced mutations?

(1) Gamma ray (2) UV-irradiation

(3) X-ray (4) Cosmic rays

21. Pollen grains of a plant whose 2n = 28 are cultured to get callus by tissue culture method. What

would be the number of chromosomes in the cells of the callus?

(1) 14 (2) 56

(3) 28 (4) 21

22. Hybrid vigour is eroded through –

(1) Repeated crossing (2) Repeated selection

(3) Vegetative propagation (4) Repeated selfing

23. Wild varieties of plants must be conserved to –

(1) Maintain ecosystem (2) Feeding wild animals

(3) Future evolution

(4) incorporate useful traits in future crop varieties

24. Central Sugar cane breeding research institute is situated at

(1) Lucknow (2) Delhi

(3) Coimbatore (4) Bhopal

25. Which is the oldest breeding method?

(1) Introduction (2) Selection

(3) Hybridisation (4) Mutation breeding




1. The set pollinated progeny of a homozygous plant constitute a

(1) Pure line (2) Mixed population (3) Mass selection (4) Heterosis

2. The reason why vegetatively reproducing crop plants are best suited for maintaining hybrid

vigour is that

(1) They can be easily propagated

(2) Once a desired hybrid has been produced, there are few chances of losing it

(3) They have a longer life span

(4) They have short life span

3. Hybrid vigour is mostly due to

(1) Heterozygosity

(2) Superiority of all the genes

(3) Homozygosity of pure characters

(4) Mixing up of cytoplasm of the male with that of female exclusively

4. An unorganized mass of cells is called

(1) Totipotent (2) Explant

(3) Callus (4) Corax

5. The ability of plant cell to give rise to an entire new plant is called

(1) Symmetry (2) Differentiation

(3) Totipotency (4) Dedifferentiation

6. A novel technique devised to produce vast quantities of strong and healthy plantlets by rapid

vegetative multiplication under controlled conditions

(1) Anther culture (2) Polymerase Chain Reaction

(3) Micropropagation (4) Protoplast fusion

7. Select the correct statement(s) –

I. IARI has released a mustard variety rich in vitamin C.

II. Pusa Sawani variety of Okra is resistant to shoot and fruit borer

III. Hairiness of leaves provides resistance to insect pests

IV. Agriculture accounts for approximately 33% of India’s GDP and employs nearly 62% of

the population

(1) I and II (2) II and III

(3) I, II, III and IV (4) None of these

8. The substance used in the tissue culture medium for induction of shoots in callus is

(1) ABA (2) GA3 (3) IAA (4) Kinetin

9. Haploid plantlets can be produced by

(1) Pollen culture (2) Cotyledon culture

(3) Embryo culture (4) Meristem culture

10. India’s wheat yield revolution in the 1960s was possible primarily due to

(1) Increased chlorophyll content (2) Mutations resulting in plant height reduction

(3) Quantitative trait mutations (4) Hybrid seeds



11. Embryo rescue is used for

(1) Establishing suspension culture

(2) Recovery of interspecific hybrids (difficult hybrids)

(3) Somatic hybridization

(4) Haploid production

12. Which of the following is the consequence of plant diseases?

(1) Reduced yield and lower quality of produce

(2) Reduced yield, lower quality of produce and increased cost of production

(3) Reduced yield, lower quality of produce and poisonous produce

(4) Reduced yield, lower quality of produce, increased cost of production and poisonous

produce

13. Select the correct statements –

(1) Our present day crop plants are entirely different from their wild ancestors as almost all our

present day crops are the result of selections carried out by the prehistoric human’s beings

(2) Almost all our present day crops are the result of selections carried out by the prehistoric

human beings

(3) Feeding of rarer plants into agriculture and horticulture trade is of great advantage to

genetic conservation


14. New methods of obtaining plant breeds includes –

(1) inducing mutations in plants and then screening for resistant plants

(2) selection among somaclonal variants

(3) plants obtained by genetic engineering

(4) All

15. Mutational breeding has produced the variety of mung bean which is resistance to –

(1) yellow mosaic virus

(2) powdery mildew

(3) Both (1) and (2)

(4) White rust

16. Gene responsible for dwarfing in wheat is

(1) dee-geo-woo-gen

(2) norin-10

(3) crygene

(4) nod gene

17. Which of the following is incorrect w.r.t. SCP?

(1) Quantitatively and qualitatively superior proteins

(2) Production involves utilisation of organisms which has high rate of biomass production and

growth

(3) Can be obtained from both unicellular and muticellular organisms

(4) 250g of Methylophillus methylotrophus can produce 20 tonnes of protein per day

18. The objectives of breeding improved nutritional quality of crops are to increase

(1) Protein content and quality only

(2) Oil/fat content and quality only



(3) Vitamin content and Mineral nutrients


19. Select the correct statement(s) –

(1) Micropropagation is the production of small plants

(2) The source of single cell protein is microbes

(3) IARI has released a mustard variety rich in vitamin C.

(4) Both b and c

20. The conventional method of breeding for resistance includes which of the following steps?

(1) Screening the germplasm for resistant sources and hybridization of selected parents

(2) Selection and evaluation of the hybrids and testing and release of new varieties

(3) Both a and b

(4) None of these

21. Which one is correct about Atlas 66?

(1) It has high protein content

(2) It has been used as a donor for improving cultivated wheat.

(3) Both (1) and (2)

(4) None of these

22. High yielding, semi dwarf varieties of rice are –

(1) Jaya and Ratna (2) Jaya, Ratna and IR-8

(3) Aruna (4) All of these

23. Cryopreservation is

A. Preservation at ultra low temperature

B. Preservation in liquid nitrogen

C. preservation through exposure to gamma rays

D. preservation of semen

(1) A and B (2) B and C

(3) C and D (4) A, B, C, D

24. Which one is a rich source of vitamin A

A. Carrot B. Spinach

C. Lemon D. Beans


(3) C and D (4) A, B, C, D

25. Which factors are responsible for development of disease in plant?

A. Susceptible host B. Aggressive pathogen

C. Conducive environment D. Excess of fertilizer


(3) C and D (4) A, B, C



Assertion & Reason Questions (Class Work)

Directions : These questions consists of two statements each, printed as Assertion (1) and Reason

(R). While answering these questions you are required to choose any one of the following four

responses.

(1) If both Assertion and the Reason are true and the Reason is a correct explanation of the Assertion.

(2) If both the Assertion and the Reason are true but the Reason is not a correct explanation of the

Assertion.

(3) If the Assertion is true but the Reason is false.

(4) If both the Assertion and the Reason are false.

1. A : Phytophthora infestans causes late blight of potato.

R : The disease is named late blight because it was discovered very late.

2. A : Plant introduction is one of the important methods of crop improvement.

R : However, plant introductions are made under the strict requirements of plant quarantine.

3. A : The discovery of Norin-10 genes was a great landmark in the history of rice breeding.

R : Using these genes, scientists produced a high yielding variety of rice called CO-312.

4. A : Allopolyploidy is more important than autopolyploidy in crop plants.

R : Allpolyploidy restores fertility to interspecific crosses.

5. A : Embroyoids are formed from somatic tissues by tissue culture technique.

R : Embryoids look like normal seed embryos.

6. A : Hybrid seeds must be produced every year to obtain maximum advantage of heterosis.

R : Heterosis is lost by inbreeding.

7. A : ‘Embryo rescue’ is culturing of young embryo, fertilised ovule or pollinated ovary.

R : ‘Embryo rescue’ is performed to protect the development of embryo.

8. A : Cloning is also known as ‘micropropagation’.

R : This technique is helpful in propagating many valuable and commercially useful plants.

9. A : Somaclonal variations occur in tissue culture processes.

R : Variations cannot occur in nature.

10. A : Protoplast fusion is one of the major advantages of tissue culture.

R : The naked protoplasts of two different plants fuse to form a hybrid.

11. A : Triticale is the first man made crop.

R : It is developed through a cross between wheat and rye.




1. On culturing the young anther of a plant a botanist got a few diploid plants along with haploid

plants. Which of the following might have given the diploid plants?

(1) Exine of pollen grain (2) Vegetative cell of pollen

(3) Cells of anther wall (4) Generative cell of pollen

(A.I.I.M.S 1980, M.P.P.M.T. 1986, B.H.U.1992)

2. Which one produce androgenic haploids in anther cultures? (CBSE 1990, DPMT 1997)

(1) Anther wall (2) Tapetal layer of anther wall

(3) Connective tissue (4) Young pollen grains

3. In Tobacco callus, which one shall induce shoot differentiation in combination of auxin and

cytokinin?

(1) Higher concentration of cytokinin and lower concentration of auxin

(2) Lower concentration of cytokinin and higher concentration of auxin

(3) Only cytokinin and no auxin

(4) Only auxin and no cytokinin (DPMT 1986, 1993, 1997)

4. In callus culture, roots can be induced by the supply of

(1) Auxin and no cytokinin (BHU 1988)

(2) Higher concentration of auxin and lower concentration of cytokinin

(3) Higher concentration of cytokinin and lower concentration of auxin

(4) Both auxin and cytokinin in equal proportions

5. Who could grow Tomato roots successfully and develop the technique of tissue culture for the

first time? (AMU 1992, 2003)

(1) Haberlandt (2) P.R. White (3) W.H. Muir (4) F.C. Steward

6. Variations observed during tissue culture of some plants are known as (AMU 1992, 2003)

(1) Clonal variations (2) Somaclonal variations

(3) Somatic variations (4) Tissue culture variations

7. Virus free plants can be obtained by (MPPMT 1992, AIIMS, 1992, 1996)

(1) Antibiotic treatment (2) Bordeaux mixture

(3) Root tip culture (4) Shoot tip culture

8. Tissue culture technique can produce indefinite number of new plants from a small parental

tissue. The economic importance of the technique is in raising (AIIMS 1992)

(1) Variants through picking up somaclonal variations

(2) Genetically uniform population of an elite species

(3) Homozygous diploid plants

(4) Development of new species

9. Haploid plant cultures are got from (CPMT 1994, CBSE, 1994, MPPMT 2000)

(1) Leaves (2) Root tip (3) Pollen grain (4) Buds

10. Somaclonal variations are the ones (BHU 1994, DPMT 1999, AIIMS 2004, 2005, 2006)

(1) Caused by mutagens (2) Produced during tissue culture

(3) Induced during sexual embryogeny (4) Caused by gamma rays

11. Plants developed in vitro culture from pollen grains are (AIIMS 1996)

(1) Androgenic haploids (2) Pollen plants

(3) Male plants (4) Sterile plants

12. In tissue/bacterial culture, glassware and nutrients are stertilised through (DPMT 1996)

(1) Water bath at 200°C (2) Dry air oven at 200°C

(3) Dehumidifier (4) Autoclave

13. Callus is (DPMT 1996)

(1) Tissue that forms embryo



(2) An insoluble carbohydrate

(3) Tissue that grows to form embryoid

(4) Unorganised actively dividing mass of cells maintained in culture.

14. The enzymes required to obtain wall-free/naked protoplasts are (BHU 1996)

(1) Cellulase and protease (2) Cellulase and pectinase

(3) Cellulase and amylase (4) Amylase and pectinase

15. Development of shoot and root in tissue culture is determined by

(AIIMS, '97 DPMT '97, BHU '97, Har PMT 2000)

(1) Cytokinin and auxin ratio (2) Enzymes

(3) Temperature (4) Plant nutrients

16. Plant raised from single germinating pollen grain under culture condition would be

(AMU 1998, Bihar PMT 2001)

(1) Diploid (2) Haploid

(3) Triploid (4) Tetraploid

17. Plant medium used widely in preparation of culture medium is got from (AIIMS 1998)

(1) Cycas revoluta (2) Cocos nucifera

(3) Pinus roxburghii (4) Borassus flabellifera

18. Clonal cell lines are got from

(1) Tissue culture (2) Tissue fractionation

(3) Tissue homogenisation (4) Tissue system (MPPMT 2000)

19. Technique used in agriculture biotechnology is

(1) Plant breeding (2) Transformation

(3) DNA replication (4) Tissue culture (MPPMT 1998)

20. Important use of agriculture biotechnology is to (MPPMT 1998)

(1) Produce pest resistance (2) Increase nitrogen content

(3) Increase plant weight (4) Decrease seed number

21. The first transgenic crop was (CBSE 1999)

(1) Pea (2) Tobacco

(3) Flax (4) Cotton

22. Technique for production of disease free plants is

(1) Clonal culture (2) Tissue culture

(3) Polyploidy (4) Hybridisation (B.V. 2000)

23. Pomato is (Kerala 2000)

(1) Somatic hybrid (2) Natural mutant

(3) Androgenic haploid (4) Somatic embryoid

24. Chemofusion and electrofusion are employed in

(1) Eugenics (2) Protoplast fusion

(3) Cloning (4) Mutations (DPMT 2001)

25. Introduction of foreign genes for improving genotype is (CBSE 1996)

(1) Tissue culture (2) Immunisation

(3) Somatic hybridisation (4) Genetic engineering

26. Which is a microbial insecticide? (AIIMS 1997)

(1) Bacillus thuringinesis (2) B.subtilis

(3) B.polymixa (4) B.brevis

27. Aquatic fern which is an excellent biofertiliser in rice fields is (CBSE 1999, 2001)

(1) Salvinia (2) Azolla (3) Marsilea (4) Pteridium

28. Which one is a biofertiliser? (JKCMEE 2000, JIPMER 2000)

(1) NPK mixture (2) Rhizobium in legume roots

(3) Rhizobium in farmyard manure (4) Green manure

29. VAM is important for (Kerala 2000)

(1) Breaking of dormancy (2) Phosphate nutrition

(3) Water uptake (4) Retarding flowering



30. Most famous nitrogen fixing bacterium/biofertilizer is (Kerala 2000, JIPMER 2000)

(1) Nitrobacter (2) Nitrosomonas

(3) Nitrosococcus (4) Rhizobium

31. Azolla possesses symbiotic association with (Wardha 2001, JKCMEE 2002)

(1) Anabaena (2) Nostoc

(3) Azospirillum (4) Rhizobium

32. Which one is a biofertilizer? (B.V. 2001, 2002)

(1) VAM (2) Sporeine

(3) Devine (4) Agent Orange

33. Azolla is used as biofertilizer as it has (DPMT 2001)

(1) Rhizobium (2) Cyanobacteria

(3) Mycorrhiza (4) Large quantity of humus

34. Biofertilisers include (JKCMEE 2002)

(1) Nitrogen fixing bacteria (2) Mycorrhiza

(3) Nitrogen fixing cyanobacteria (4) All the above

35. Mycorrhiza acts as (BHU 2002)

(1) Mechanical tissue (2) Root hair in adverse conditions

(3) Modified root (4) Organ for vegetative propagation

36. Polyethylene glycol method is used for (AIPMT 2009)

(1) seedless fruit production (2) energy production from sewage

(3) gene transfer without a vector (4) biodiesel production

37. Differentiation of shoot in tissue culture is controlled by (CBSE 2003)

(1) High auxin : cytokinin ratio (2) High cytokinin : auxin ratio

(3) High gibberellin : auxin ratio (4) High gibberellin : cytokinin ratio

38. In crop improvement programmes virus-free clones can be obtained through

(AIPMT 2008; KCET 2009)

(1) grafting (2) hybridization

(3) embryo culture (4) shoot apex culture

39. Azolla is used as a biofertiliser because it (AIIMS 2003)

(1) Multiplies very fast to produce massive biomass

(2) Has association of nitrogen fixing Rhizobium

(3) Has association of nitrogen fixing cyanobacteria

(4) Has association of mycorrhiza

40. A protein supplement is (Har. PMT 2003)

(1) Chlorella (2) Spirulina

(3) Gracilaria (4) All the above

41. Which one of the following is useful in rice fields? (Pb PMT 2003)

(1) Rhizobium (2) Clostridium

(3) Anabaena (4) Ferrobacterium

42. Golden Rice developed through transgenic technique is enriched with

(Orissa 2003, CBSE 2005)

(1) High lysine (2) High methionine

(3) High glutenine (4) High vitamin A content

43. A plant having nitrogen fixing bacteria is (CPMT 2003)

(1) Cotton (2) Wheat (3) Gram (4) Mustard

44. Genetically engineered crop which has been recently introduced in India is (AIEEE 2003)

(1) Golden Rice (2) Slow ripening Tomato

(3) Herbicide tolerant Maize (4) Bt Cotton

45. Inherent capacity of a cell to regenerate the whole organism is called

(Kerala 2003, Manipur 2005, Orissa 2006) (1) Totipotency (2) Ontogeny

(3) Differentiation (4) Proliferation



46. Insect resistant transgenic cotton has been developed by inserting a piece of DNA from

(1) An insect (2) Wild relative of Cotton

(3) A bacterium (4) A virus (CPMT 2004)

47. Insecticide pyrethrum is prepared from

(1) Vetiveria (2) Chrysanthemum

(3) Tephrosia (4) Cymbopogon (CPMT 2004)

48. Which one of the following is being utilised as a source of biodiesel in the Indian countryside?

(1) Pongamia (2) Euphorbia

(3) Beetroot (4) Sugarcane (CBSE 2007)

49. A genetically engineered micro-organism used successfully in bioremediation of oil spills is a

species of: (CBSE 2007)

(1) Bacillus (2) Pseudomonas

(3) Trichoderma (4) Xanthomonas

50. In maize, hybrid vigour is exploited by (CBSE 2007)

(1) Inducing mutations (2) Bombarding the seeds with DNA

(3) Crossing of two inbred parental lines

(4) Harvesting seeds from the most productive plants

51. ‘Jaya’ and ‘Ratna’ developed for green revolution in India are the varieties of (CBSE 2011)

(1) rice (2) wheat

(3) bajra (4) maize

52. Which one of the following shows maximum genetic diversity in India? (CBSE 2011)

(1) Rice (2) Maize

(3) Mango (4) Groundnut

53. A collection of plants and seeds having diverse alleles of all the genes of a crop is called

(1) Germplasm (2) gene library (CBSE 2011)

(3) genome (4) herbarium

54. ‘Himgiri’ developed by hybridization and selection for disease resistance against rust

pathogens is a variety of

(1) Maize (2) sugarcane (CBSE 2011)

(3) wheat (4) chilli

55. Powdery mildew of wheat is caused by a species of (RPMT 2011)

(1) Puccinia (2) Erysiphe

(3) Ustilago (4) Albugo

56. Which part would be most suitable for raising virus-free plants for micropropagation?

(1) Bark (2) Vascular tissue (CBSE 2012)

(3) Meristem (4) Node

57. Consider the following four statements (I – IV) and select the option which includes all the

correct ones only

I. Single cell Spirulina can produce large quantities of food rich in protein, minerals, vitamins

etc.

II. Body weight-wise the microorganism Methylophilus methylotrophus may be able to

produce several times more proteins than the cows per day. (CBSE 2012)

III. Common button mushrooms are a very rich source of vitamin – C.

IV. A rice variety has been developed which is very rich in calcium.

(1) Statement III, IV (2) Statements I, III and IV

(3) Statement II, III and IV (4) Statements I, II

58. The final stage in the tissue culture programme before the new plants are taken out for

cultivation in the fields in known as (KCET 2012)

(1) embryogenesis (2) micropropagation

(3) hardening (4) caulogenesis

59. Breeding of crops with high level of minerals, vitamins and proteins called



(1) somatic hybridization (2) biofortification (AIIMS 2012)

(3) biomagnification (4) micropropagation

60. In plant tissue culture, the callus tissues can be regenerated into complete plantlets primarily by

altering the concentration of (WB JEE 2012)

(1) sugars (2) vitamins

(3) amino acids (4) hormones

61. In plant breeding programmes, the entire collection (of plants/seeds) having all the diverse

alleles for all genes in a given crop is called (NEET 2013)

(1) germplasm collection.

(2) selection of superior recombinants

(3) cross – hybridization among the selected parents.

(4) evaluation and selection of parents.

62. To obtain virus - free healthy plants from a diseased one by tissue culture technique, which

part/ parts of the diseased plant will be taken ? (AIPMT 2014)

(1) Both apical and axillary meristems (2) Epidermis only

(3) Apical meristem only (4) Palisade parenchyma

63. Which of the following enhances or induces fusion of protoplasts? (AIPMT 2015)

(1) Polyethylene glycol and sodium nitrate

(2) IAA and kinetin

(3) IAA and gibberellins

(4) Sodium chloride and potassium chloride

64. A technique of micropropagation is: (RE-AIPMT 2015)

(1) Somatic embryogenesis (2) Protoplast fusion

(3) Embryo rescue (4) Somatic hybridization

65. Golden rice is a genetically modified crop plant where the incorporated gene is meant for

biosynthesis of (RE-AIPMT 2016)

(1) Vitamin A (2) Vitamin B (3) Vitamin C (4) Omega 3

66. A system of rotating crops with legume or grass pasture to improve soil structure and fertility

is called: (NEET-UG PHASE I 2016)

(1) Shifting agriculture (2) Ley farming (3) Contour farming (4) Strip farming

67. Homozygous purelines in cattle can be obtained by: (NEET 2017)

(1) mating of related individuals of same breed.

(2) mating of unrelated individuals of same breed.

(3) mating of individuals of different breed.

(4) mating of individuals of different species.

————



EXERCISE (KEY)

LEVEL-I (CLASS WORK)

1. (2)

2. (2)

3. (4)

4. (4)

5. (4)

6. (1)

7. (1)

8. (3)

9. (4)

10. (2)

11. (2)

12. (3)

13. (4)

14. (1)

15. (3)

16. (4)

17. (2)

18. (1)

19. (1)

20. (3)

21. (1)

22. (4)

23. (4)

24. (3)

25. (2)


1. (1)

2. (2)

3. (1)

4. (3)

5. (3)

6. (3)

7. (3)

8. (4)

9. (1)

10. (2)

11. (2)

12. (2)

13. (4)

14. (4)

15. (3)

16. (2)

17. (3)

18. (4)

19. (2)

20. (3)

21. (3)

22. (1)

23. (1)

24. (1)

25. (4)


1. (3)

2. (2)

3. (4)

4. (1)

5. (2)

6. (1)

7. (1)

8. (2)

9. (3)

10. (2)

11. (1)

PREVIOUS YEARS QUESTIONS ( HOME WORK)

1. (3)

2. (4)

3. (1)

4. (2)

5. (2)

6. (2)

7. (4)

8. (2)

9. (3)

10. (2)

11. (1)

12. (4)

13. (4)

14. (2)

15. (1)

16. (2)

17. (2)

18. (1)

19. (4)

20. (1)

21. (2)

22. (2)

23. (1)

24. (2)

25. (4)

26. (1)

27. (2)

28. (2)

29. (2)

30. (4)

31. (1)

32. (1)

33. (2)

34. (4)

35. (2)

36. (3)

37. (2)

38. (4)

39. (3)

40. (2)

41. (3)

42. (4)

43. (3)

44. (4)

45. (1)

46. (3)

47. (2)

48. (1)

49. (2)

50. (3)

51. (1)

52. (1)

53. (1)

54. (3)

55. (2)

56. (3)

57. (4)

58. (3)

59. (2)

60. (4)

61. (1)

62. (1)

63. (1)

64. (1)

65. (1)

66. (2)

67. (1)

————

INDEX

Topic Name Page No


Exercise 81- 98

Level–I 81-83

Level–II 84-86



Answer Key 99-99


Introduction

Levels of Ecological Organization

Organism and Its Environment

Environment Habitat and Niche

Environmental Factors

Major Abiotic Factors

Responses to Abiotic Factors

Adaptations

Populations

Population Attributes

Population Interactions

ORGANISMS AND POPULATIONS

Organisms and Populations Rg.-Bot. XII-19-21


INTRODUCTION

• In ecology interaction between living organisms and their environment is studied. Term ecology

was used for the first time by Reiter (1885), but it was properly defined and given its present

meaning by German biologist Ernst Haeckel (1869).

• Warming is regarded as father of plant ecology.

• Environmental problems such as degradation of land, use of pesticides, pollution, global

warming, destruction of wild life and forests, etc., are major cause of concern for present day

man because these are directly related with present day man as well as future generation to come.

Such problems can be addressed only by ecological studies and corrective measures should be

taken in time to save our earth.

• Ecology has two main branches, (i) Autecology and (ii) Synecology. Autecology is the study of

reciprocal relationship between individual organism or species and its environment.

Communities and their environment are studied in synecology.

• Diversity is a characteristic of living organisms. There are many threads which weave the

different areas of biological information into a unifying principle. Ecology is one such thread

which gives us a holistic perspective to biology.

• The essence of ecological understanding is to know how organisms, while remaining an

individual, interact with other organisms and physical habitats as a group and hence behave like

organised wholes, i.e., population, community, ecosystem or even as the whole biosphere.

Ecology explains to us all this.

• Ramdeo Misra is revered as the Father of Ecology in India. His research laid the foundations for

understanding of tropical communities and their succession, environmental responses of plant

populations and productivity and nutrient cycling in tropical forest and grassland ecosystems.

• Due to his efforts, the Government of India established the National Committee for

Environmental Planning and Coordination (1972) which, in later years, paved the way for

the establishment of the Ministry of Environment and Forests (1984).

• Our living world is fascinatingly diverse and amazingly complex. We can try to understand its

complexity by investigating processes at various levels of biological organisation –

macromolecules, cells, tissues, organs, individual organisms, population, communities and

ecosystems and biomes. At any level of biological organisation we can ask two types of

questions – for example, when we hear the bulbul singing early morning in the garden, we may

ask – ‘How does the bird sing ?’ Or, ‘Why does the bird sing?’ The ‘how-type’ questions seek

the mechanism behind the process while the ‘why- type’ questions seek the significance of the

ORGANISMS AND POPULATIONS



process. For the first question in our example, the answer might be in terms of the operation of the

voice box and the vibrating bone in the bird, whereas for the second question the answer may lie

in the bird’s need to communicate with its mate during breeding season.

• Ecology is basically concerned with four levels of biological organisation – organisms,

populations, communities and biomes.

LEVELS OF ECOLOGICAL ORGANIZATION

• Organisms: Organisms are the basic unit of study in ecology. Organisms belonging to same

species interbreed and produce fertile offspring under natural condition. Species is a genetically

and reproductively closed group, consisting of same type of organisms.

• Population: Group of individuals of plants or animals of a species inhabiting a particular area is

called population.

• Community: All the populations of different species in a particular area is called community.

Various types of interaction occur in between the organisms of the same species as well as

between the members of different species, in a community.

• Biome: It is a large regional unit delimited by a specific climatic zone having a particular major

vegetation zone and its associated fauna e.g., tropical rain forest, desert biome, temperate

coniferous forest, etc.

ORGANISM AND ITS ENVIRONMENT

• Ecology at the organismic level is essentially physiological ecology which tries to understand how

different organisms are adapted to their environments in terms of not only survival but also

reproduction.

• The rotation of our planet around the Sun and the tilt of its axis cause annual variations in the

intensity and duration of temperature, resulting in distinct seasons. These variations together

with annual variation in precipitation (remember precipitation includes both rain and snow)

account for the formation of major biomes such as desert, rain forest and tundra (Figure).

Biome distribution with respect to annual temperature and precipitation



• Regional and local variations within each biome lead to the formation of a wide variety of habitats.

Major biomes of India are shown in Figure.

• On planet Earth, life exists not just in a few favourable habitats but even in extreme and harsh

habitats – scorching Rajasthan desert, perpetually rain-soaked Meghalaya forests, deep ocean

trenches, torrential streams, permafrost polar regions, high mountain tops, boiling thermal springs,

and stinking compost pits, to name a few. Even our intestine is a unique habitat for hundreds of

species of microbes.

(1) (2)

(3) (4)

Major biomes of India : (1) Tropical rain forest; (2) Deciduous forest; (3) Desert; (4) Sea coast

HABITAT AND NICHE

• The place where an organism lives is called its habitat. Functional role of an organism in the

ecosystem along with physical space, which it occupies, is called its ecological niche. Term

niche was given by Grinnel.

• Each species has a distinct niche in the ecosystem. No two species can occupy same niche in the

same ecosystem for long and one species replaces another. This is called competitive exclusion

principle or Gause hypothesis. Organisms, which occupy the same niche in different habitats,

are called ecological equivalents.

• The key elements that lead to so much variation in the physical and chemical conditions of

different habitats are temperature, water, light and soil.



• The physico-chemical (abiotic) components alone do not characterise the habitat of an organism

completely; the habitat includes biotic components also – pathogens, parasites, predators and

competitors – of the organism with which it interacts constantly. It is assumed that over a period of

time, the organism has through natural selection, evolved adaptations to optimise its survival and

reproduction in its habitat.

ENVIRONMENT

Sum total of all living or biotic and non-living or abiotic factors that influence an organism is

called environment. Some environmental components function as resources while others work as

regulatory factors.

ENVIRONMENTAL FACTORS

• Environmental factors affect the life of living organisms. These factors are broadly categorized

into two groups, abiotic and biotic factors.

• Physical or abiotic factor: This includes:

Climatic factors such as air, light, atmospheric humidity, rain, temperature, etc.

Edaphic factors which are related with soil.

Topographic factors, which are related with, surface behavior of earth like steepness, altitude,

direction of mountain chains and valleys.

Fire as an ecological factor also play important role in distribution of plants and animals.

• Biotic factors: These include producers or plants, consumers or animals and decomposers or

microorganisms.

MAJOR ABIOTIC FACTORS

Climate

Short-term properties of the atmosphere such as precipitation, temperature, humidity, sunshine,

pressure, wind and cloud cover at a particular area and time are called weather. Average weather

conditions of that area over a long period of time, say for a season or an year is called its climate.

Temperature and rainfall are the two most important factors which determine the climate of an

area. On the basis of variations in mean temperature along latitude the main climatic regions are

tropical (0°–20° latitude) subtropical (20°–40° latitude), temperate (40°–60° latitude), Arctic

and Antarctic (60°–80° latitude). As we move from equator to poles or from lower latitude to

higher latitude temperature decreases. Similarly temperature also decreases as we move from

lower altitude to higher altitude.

Microclimate

Often environment in which organisms live is quite different from overall climate of the area

e.g., under a tree temperature and humidity are quite different in comparison to average climate

of the area. The climatic conditions that prevail at a local scale or in area of limited size is called

microclimate.



Temperature:

• Temperature is the most ecologically relevant environmental factor the average temperature

on land varies seasonally, decreases progressively from the equator towards the poles and from

plains to the mountain tops. The vertical temperature gradient over earth surface is called lapse

rate. Its value is 6.5°C per 1000 meters elevation.

• It ranges from subzero levels in polar areas and high altitudes to >500C in tropical deserts in

summer. There are, however, unique habitats such as thermal springs and deep-sea hydrothermal

vents where average temperatures exceed 1000 C. It is general knowledge that mango trees do not

and cannot grow in temperate countries like Canada and Germany, snow leopards are not found in

Kerala forests and tuna fish are rarely caught beyond tropical latitudes in the ocean.

• The significance of temperature to living organisms is that it affects the kinetics of enzymes and

through it the basal metabolism, activity and other physiological functions of the organism.

• A few organisms can tolerate and thrive in a wide range of temperatures (they are called eurythermal ),

but, a vast majority of them are restricted to a narrow range of temperatures (such organisms are called

stenothermal ). The levels of thermal tolerance of different species determine to a large extent their

geographical distribution.

• In water bodies temperature varies with depth which is called thermal stratification. During

summer, temperature of upper layer of water is higher than the lower layer. The upper layer is

called epilimnion while lower layer is called hypolimnion. These two layers are separated by a

narrow transition zone called thermocline. During winter, in a temperate lake, water is at freezing

temperature on the surface, whereas in the lower layer temperature is about 4°C. The surface

water is cooled during autumn, and warmed in spring. This results in a free mixing of water in the

whole water body and known as autumn and spring turnover respectively. It results in vertical

mixing of oxygen and nutrients, which results in rich growth of algae or bloom formation.

• Altitude (height above the sea level) and latitude (distance from equator) have effect on

temperature, which in turn affect type of vegetation. Effect of altitude and latitude are almost

same on temperature and vegetation. The types of vegetation from sea level to increasing altitudes

are tropical or evergreen forest, xerophytic plants or deserts, deciduous vegetation, conifers (e.g.,

Pinus, Taxus, Cedrus, Picea, etc.) alpine vegetation (Rhododendron and Juniperus) which are

found at 3600 m or 12,000 ft above sea level and tundra region where small grasses like

Saxifraga, Primula and lichens, etc., occur. Almost similar change in vegetation occurs with

latitude, i.e., from equator to poles.

• Effect on reproduction (flowering): Temperature is also an important factor affecting flowering

in plants. Low temperature treatment (0–6°C), i.e., vernalization or springification is responsible

for enhancing flowering in plants.



• Temperature and Morphology: Several structural modifications are induced in animals by

temperature.

According to Jordan, fishes living in water

characterized by low temperature are said to

have more vertebrae than those of the warm

water forms (Jordan’s rule).

Animals living in cold regions tend to be

large, for example polar bears and whales,

whilst animals living in hot climates are

generally smaller. This phenomenon is

known as Bergman’s rule.

Protruding parts such as tails, ears or legs

tend to be shorter in colder climates than in

warmer climates (Allen’s rule).

Colours tend to be darker in warm moist

climates and lighter in cold dry climate

(Gloger’s rule)

Fig.: variation in ear length shown by three

species of fox, each occupies a different

geographical region (Allen’s rule)

Birds of colder areas have narrow and

acuminate wings while those of warmer

areas have broader wings (Rensch’s rule).

• Temperature and Cyclomorphosis:

Cyclomorphosis is a phenomenon exhibited by

certain planktonic organisms like Daphnia,

which change their body form with the seasonal

changes of temperature. In the winter, these

crustaceans have a round head. During spring a

helmet like projection develops, which gets

reduced in autumn and disappears in winter.

Fig.: Seasonal variation in body form of

Daphnia

Water:

• Next to temperature, water is the most important factor influencing the life of organisms. In fact, life

on earth originated in water and is unsustainable without water. Its availability is so limited in

deserts that only special adaptations make it possible to live there. The productivity and

distribution of plants is also heavily dependent on water.

• Those organisms living in oceans, lakes and rivers should not face any water-related problems, it is

not true. For aquatic organisms the quality (chemical composition, pH) of water becomes important.

The salt concentration (measured as salinity in parts per thousand), is less than 5 per cent in inland

waters, 30-35 per cent the sea and > 100 per cent in some hypersaline lagoons.

• Some organisms are tolerant of a wide range of salinities (euryhaline) but others are restricted to

a narrow range (stenohaline). Many freshwater animals cannot live for long in sea water and vice

versa because of the osmotic problems, they would face.



• Rainfall is the chief source of precipitation. Out of the total rainfall, 45% is run away or runoff

water, which flows to rivers and oceans, 35% is evaporated and rest 20% is absorbed by the

ground. Amount and timings of rainfall determine the type of vegetation of an area, e.g.,

If no rainfall or scanty rainfall throughout the year then xerophytic vegetation or deserts occur.

If more rainfall in summer and less in winter, then grasslands will develop.

If more rainfall in winter and less in summer, then thick, dwarf shrubs with leathery leaves,

i.e., sclerophyllous vegetation occurs.

If rainfall occurs throughout the year then evergreen forests, e.g., tropical rain forests occur.

Light:

• Since plants produce food through photosynthesis, a process which is only possible when sunlight is

available as a source of energy, we can quickly understand the importance of light for living

organisms, particularly autotrophs.

• Visible part of light falls between 400–700 nm, which is mainly utilized by plants. It is called

photosynthetically active radiation (PAR). Radiation beyond 700 nm is called infrared while

between 100-400 nm wavelength is called ultra violet (UV). UV radiation can be categorized

into three types UV-C (100 nm–280 nm), UV-B (280nm–320nm) and UV-A (320 nm–400 nm).

Out of these, UV-C radiation is lethal for organisms while UV-B is also harmful.

• Many species of small plants (herbs and shrubs) growing in forests are adapted to photosynthesise

optimally under very low light conditions because they are constantly overshadowed by tall,

canopied trees. Many plants are also dependent on sunlight to meet their photoperiodic requirement

for flowering. For many animals too, light is important in that they use the diurnal and seasonal

variations in light intensity and duration (photoperiod) as cues for timing their foraging,

reproductive and migratory activities. The availability of light on land is closely linked with that

of temperature since the sun is the source for both. But, deep (>500m) in the oceans, the

environment is perpetually dark and its inhabitants are not aware of the existence of a celestial source

of energy called Sun.

• The spectral quality of solar radiation is also important for life. The UV component of the visible

spectrum are available for marine plants living at different depths of the ocean.

• Light is an important limiting factor for plants in deep water bodies such as lakes and oceans.

Different zones in water bodies on the basis of penetration of light are–

Littoral zone: It is the shallow zone around the edges where depth of water is not much, so

the rooted plant grows.

Limentic zone: It is open water zone beyond the littoral zone where depth of the water is so

much that only phytoplankton or free-floating plants can grow. Its depth may be between 20–

40 metres depending upon the turbidity of water.

Profundal zone: It is the dark zone present below limnetic zone where light cannot penetrate.

Blue light has maximum penetration power while red light has minimum for the water. The

floor of the water bodies is called benthic region and organisms living there are called benthic



organism, e.g., snails, slugs and micro-organisms.

• Effect of light on growth and development: Different plants have different light requirements

and hence plants are divided into two main types on the basis of light requirement for growth and

development.

Heliophytes or Photophilous or Sun loving plants: These grow in high light condition, e.g.,

Sunflower.

Sciophytes or Heliophobous or Photophobous or Shade loving plants: These grow in poor

light intensity, e.g., Abies, Picea, Taxus, etc.

Soil (Edaphic Factors):

• The factors, which affect the plants through soil, are called edaphic factors. Soil is very important

ecological factor as it provides water, minerals or nutrients and support. Warming (1909) was the

first ecologist who recognized the importance of soil as ecological factor and he divided plants

into five different types on the basis of the soil conditions, i.e., halophytes (plants growing in

salty or saline soil), oxylophytes (plants growing in acidic soil), psammophytes (plants growing

in sandy soil), chasmophytes (plants growing in rock crevices) and lithophytes (plants growing

on rocks).

• The nature and properties of soil in different places vary; it is dependent on the climate, the

weathering process, whether soil is transported or sedimentary and how soil development

occurred.

• Various characteristics of the soil such as soil composition, grain size and aggregation determine

the percolation and water holding capacity of the soils. These characteristics along with parameters

such as pH, mineral composition and topography determine to a large extent the vegetation in any

area. This is in turn dictates the type of animals that can be supported. Similarly, in the aquatic

environment, the sediment-characteristics often determine the type of benthic animals that can thrive

there.

Components of soil complex and their characteristic

• Mineral particles: These are the chief components of soil complex and are formed by

weathering of rocks. Depending upon size of mineral particles, soils are of following types:

Clay: If particle size is less than 0.002 mm

Silt: If particle size is 0.002–0.02 mm

Fine sand: If the particles size is 0.02–0.2 mm

Coarse sand: 0.2 –2 mm

Gravel or Stone: More than 2 mm

Thus the correct sequence according to increasing particle size is

Clay > Slit > Fine sand > Coarse sand < Gravel.



• Soil texture: the proportion of particles of different sizes determine the soil texture and on this

basis soils are of following types:

Clayey: 85% clay + 15% sand or silt or both.

Sandy: 80% or more of sandy the remaining being silt and clay.

Loamy: 50% clay + 50% sand or silt or both.

Loamy soil is best for plant growth.

Soil texture determines, soil air, soil water and root penetration properties.

RESPONSES TO ABIOTIC FACTORS

The abiotic conditions of many habitats may vary drastically in time, how do the organisms living in

such habitats cope or manage with stressful conditions? Why a highly variable external environment

should bother organisms after all. One would expect that during the course of millions of years of their

existence, many species would have evolved a relatively constant internal (within the body)

environment that permits all biochemical reactions and physiological functions to proceed with

maximal efficiency and thus, enhance the overall ‘fitness’ of the species. This constancy, for

example, could be in terms of optimal temperature and osmotic concentration of body fluids. Ideally

then, the organism should try to maintain the constancy of its internal environment (a process called

homeostasis) despite varying external environmental conditions that tend to upset its

homeostasis.

Diagrammatic representation of organismic response

(i) Regulate: Some organisms are able to maintain homeostasis by physiological (sometimes

behavioural also) means which ensures constant body temperature, constant osmotic

concentration, etc. All birds and mammals, and a very few lower vertebrate and invertebrate

species are indeed capable of such regulation (thermoregulation and osmoregulation).

Evolutionary biologists believe that the ‘success’ of mammals is largely due to their ability to

maintain a constant body temperature and thrive whether they live in Antarctica or in the Sahara

desert.

The mechanisms used by most mammals to regulate their body temperature are similar to the ones that

we humans use. We maintain a constant body temperature of 370C. In summer, when outside



temperature is more than our body temperature, we sweat profusely. The resulting evaporative

cooling, similar to what happens with a desert cooler in operation, brings down the body

temperature. In winter when the temperature is much lower than 370C, we start to shiver, a kind of

exercise which produces heat and raises the body temperature. Plants, on the other hand, do

not have such mechanisms to maintain internal temperatures.

(ii) Conform: An overwhelming majority (99 per cent) of animals and nearly all plants cannot

maintain a constant internal environment. Their body temperature changes with the ambient

temperature.

In aquatic animals, the osmotic concentration of the body fluids changes with that of the ambient

water osmotic concentration. These animals and plants are simply conformers. Considering the

benefits of a constant internal environment to the organism, we must ask why these conformers

had not evolved to become regulators. Recall the human analogy we used above; much as they

like, how many people can really afford an air conditioner? Many simply ‘sweat it out’ and

resign themselves to suboptimal performance in hot summer months. Thermoregulation is

energetically expensive for many organisms. This is particularly true for small animals like

shrews and humming birds. Heat loss or heat gain is a function of surface area. Since small animals

have a larger surface area relative to their volume, they tend to lose body heat very fast when it is

cold outside; then they have to expend much energy to generate body heat through metabolism.

This is the main reason why very small animals are rarely found in Polar Regions.

During the course of evolution, the costs and benefits of maintaining a constant internal

environment are taken into consideration. Some species have evolved the ability to regulate, but only

over a limited range of environmental conditions, beyond which they simply conform.

If the stressful external conditions are localized or remain only for a short duration, the

organism has two other alternatives.

(iii) Migrate: The organism can move away temporarily from the stressful habitat to a more

hospitable area and return when stressful period is over. In human analogy, this strategy is like a

person moving from Delhi to Shimla for the duration of summer. Many animals, particularly

birds, during winter undertake long-distance migrations to more hospitable areas. Every winter

the famous Keolado National Park (Bhartpur) in Rajasthan host thousands of migratory birds

coming from Siberia and other extremely cold northern regions.

(iv) Suspend: In bacteria, fungi and lower plants, various kinds of thick-walled spores are formed which

help them to survive unfavourable conditions – these germinate on availability of suitable

environment. In higher plants, seeds and some other vegetative reproductive structures serve as

means to tide over periods of stress besides helping in dispersal – they germinate to form new plants

under favourable moisture and temperature conditions. They do so by reducing their metabolic

activity and going into a date of ‘dormancy’.

In animals, the organism, if unable to migrate, might avoid the stress by escaping in time. The

familiar case of bears going into hibernation during winter is an example of escape in time.

Some snails and fish go into aestivation to avoid summer–related problems-heat and

desiccation. Under unfavourable conditions many zooplankton species in lakes and ponds are



known to enter diapause, a stage of suspended development.

ADAPTATIONS

• While considering the various alternatives available to organisms for coping with extremes in their

environment, we have seen that some are able to respond through certain physiological adjustments

while others do so behaviourally (migrating temporarily to a less stressful habitat). These responses

are also actually, their adaptations. So, we can say that adaptation is any attribute of the organism

(morphological, physiological, behavioural) that enables the organism to survive and reproduce

in its habitat.

• Many adaptations have evolved over a long evolutionary time and are genetically fixed.

Example:

• In the absence of an external source of water, the kangaroo rat in North American deserts is

capable of meeting all its water requirements through its internal fat oxidation (in which water

is a by product). It also has the ability to concentrate its urine so that minimal volume of water

is used to remove excretory products.

• Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in

deep pits to minimise water loss through transpiration. They also have a special photosynthetic

pathway (CAM) that enables their stomata to remain closed during day time.

• Some desert plants like Opuntia, have no leaves – they are reduced to spines– and the

photosynthetic function is taken over by the flattened stems.

• Mammals from colder climates generally have shorter ears and limbs to minimise heat loss.

(This is called the Allen’s Rule.)

• In the polar seas aquatic mammals like seals have a thick layer of fat (blubber) below their skin

that acts as an insulator and reduces loss of body heat.

• Some organisms possess adaptations that are physiological which allow them to respond

quickly to a stressful situation at high altitude place (>3,500m Rohtang Pass near Manali and

Mansarovar, in China occupied Tibet) we experienced what is called altitude sickness. Its

symptoms include nausea, fatigue and heart palpitations. This is because in the low

atmospheric pressure of high altitudes, the body does not get enough oxygen. But, gradually

you get acclimatised and stop experiencing altitude sickness. The body compensates low

oxygen availability by increasing red blood cell production, decreasing the binding capacity of

hemoglobin and by increasing breathing rate.

• In most animals, the metabolic reactions and hence all the physiological functions proceed

optimally in a narrow temperature range (in humans, it is 370C). But there are microbes

(archaebacteria) that flourish in hot springs and deep sea hydrothermal vents where

temperatures far exceed 1000C. How is this possible?

• Many fish thrive in Antarctic waters where the temperature is always below zero.

• A large variety of marine invertebrates and fish live at great depths in the ocean where the

pressure could be >100 times the normal atmospheric pressure that we experience. Organisms

living in such extreme environments show a fascinating array of biochemical adaptations.



• Some organisms show behavioral responses to cope with variations in their environment.

Desert lizards lack the physiological ability that mammals have to deal with the high

temperatures of their habitat, but manage to keep their body temperature fairly constant by

behavioural means. They bask in the sun and absorb heat when their body temperature drops

below the comfort zone, but move into shade when the ambient temperature starts increasing.

Some species are capable of burrowing into the soil to hide and escape from the above-ground

heat.

Strategies of Adaptations of Plants

Plants possess special traits that help them to tolerate wide range of light regimes, dry condition, high

temperature; water saturated conditions as well as saline environments. Flowers have evolved special

structure to ensure pollination by insects or other animals. Plants have developed various

mechanisms to deal with stress conditions of the environment.

Plant Adaptations to Light Regime

• Not only individual plant but also plant communities show adaptations to different intensities

of light. Plants that have adapted to bright sunlight are called sun plants or heliophytes while

those growing in partial shade or low intensity light are called shade plants or sciophytes.

• In a forest, plants get arranged in various strata according to their shade tolerance. The

phenomenon is called stratification or layering.

• Heliophytes are adapted to high intensity of light, and have higher temperature optima for

photosynthesis, and have high rates of respiration. On the contrary, sciophytes possess low

photosynthetic, respiratory and metabolic activities. Ferns and herbaceous plants growing on

the ground under the dense canopy of three, is shade tolerate plants.

Adaptations in Plants to Water Scarcity and Heat

Plants living under water scarcity are called xerophytes. They are of four types:

(i) Ephemerals or Drought Escapers: These plants grow during brief rainy season. During that

period they flower, set seed and during rest of the unfavourable xeric condition they survive as

seed and remain dormant, e.g., Boerhaavia, Tribulus terrestris, Euphorbia prostrata.

(ii) Annuals or Drought Evaders: These plants grow during rainy season but live for a few

months even after stoppage of rain. They have morphological and anatomical adaptations to

reduce transpiration, e.g., Echinops echinata, Solanum surattense.

(iii) Succulents or Drought Resistant: Such plants have fleshy organs, which store water.

Succulents face scarcity of water in external environment only though internally plenty of

water is available. Fleshy organ responsible for storage of water may be fleshy stem

(chylocauly, e.g., Opuntia, Euphorbia, Asparagus) or fleshy leaves (chylophylly, e.g., Aloe,

Agave) or fleshy roots (chylorhizy, e.g., Asparagus). Leaves are reduced to spines, whereas

stems are modified into phylloclade or cladode (e.g., cacti). Stems and leaves possess very

thick cuticle and sunken stomata, which open during night only (scotoactive). Succulents



perform CAM pathway of photosynthesis.

(iv) Non succulent Perennial or Drought Endurer Xerophytes: These are considered as true

xerophytes, which face scarcity of water in both external and internal environment, e.g.,

Nerium, Casuarina, Acacia, etc. These have extensive root system that spreads along the soil

surface to absorb maximum amount of water. They possess waxy coating on leaves, sunken

stomata, reduced leaf blades, etc., to reduce transpiration.

Many tropical plants, particularly grasses which grow in heat and arid climates, possess C4

pathway of photosynthesis and perform better in low soil water environments. Such plants,

therefore, use less water to achieve higher rates of photosynthesis, particularly at higher

temperature.

Many xerophytes may accumulate proline (an amino acid) in the cells to maintain osmotic and

water potential in their leaves. The heat shock proteins (Chaperonins) provide physiological

adaptations to plants to high temperature. These proteins help other proteins to maintain their

structure and avoid denaturation at high temperature.

Plant adaptations in Aquatic environment

• Plants living is aquatic environment are called hydrophytes. Hydrophytes are of five types– free

floating (e.g., Lemna, Wolffia, Pistia, Trapa, etc.,) floating leaved anchored (e.g., Marsilea),

Submerged floating (e.g., Ceratophyllum, Utricularia, etc,), Submerged rooted (e.g., Hydrilla,

Vallisnaria, Potamogeton, Chara, etc.), and rooted emergent (e.g., Nymphaea, Typha,

Ranunculus, Sagittaria, etc.).

• Hydrophytes are characterized by the presence of mucilage, absence of poorly developed roots,

absence or poorly developed roots, absence of root hair and mechanical tissue. They possess

aerenchyma in the leaves and petioles. Aerenchyma helps to transport oxygen produced during

photosynthesis and permits its free diffusion to other parts, including roots located in anaerobic

soil. These tissues also impart buoyancy to the plants.

• Inflated roots in Ludwigia and petioles and Eichhornia keep the plants floating on the surface of

water. Heterophylly is common in partially submerged hydrophytes (e.g., Ranunculus).

Plant adaptation in Saline environment

• Plant growing is saline soil are called halophytes. Such plants are adapted to grow in high

concentration of salts (e.g., NaCl, MgCl2, MgSO4, etc) in soil or water. They occur in tidal

marshes and coastal dunes, mangroves and saline soils. They have the ability not only to tolerate

high concentrations of salts but also to obtain water from the same.

• Halophytes inhabiting hot and dry conditions may become succulent and store water and

mucilage in their large cells to dilute the ion concentration of salts.

• Mangrove plants are found in marshy conditions of tropical deltas and along ocean edges. Some

species of mangroves (e.g., Avicennia, Atriplex, Spartina, Aegiatilis, etc.) excrete salts through

chalk or salt glands on the leaves. Others excrete salt from their roots. Many mangrove plants

have high salt concentration and osmotic potential. Dunaliella species (green and holophytic

algae found in hyper saline lakes) can tolerate saline conditions by accumulating glycerol in the



cells, which helps in osmoregulation.

• In mangrove forests, Avicennia and Rhizophora are the dominant. Halophytes have developed

special adaptations like pneumatophores, prop and stilt roots and vivipary to cope with saline and

anaerobic conditions in wetlands. Pneumatophores help to take up O2 from the atmosphere and

transport it to the main roots. Prop and stilt roots give support to the plants. Vivipary permits

plants to escape the effect of salinity on seed germination.

Adaptation to oligotrophic soils

• The oligotrophic soils contain low amounts of nutrients. Such type of soils generally develops in

old and geologically stable areas, e.g., tropical rain forest regions. Nutrient retention capacity of

such soils is poor due to intense weathering and high rates of leaching. In such soils, nutrient

accumulation in vegetation is high.

• Many plants growing in nutrient poor soils possess mycorrhizae, which help in efficient

absorption of nutrients (e.g., phosphorus).

• On the basis of their location, mycorrhizae are of two types, ectomycorrhizae and

endomycorrhizae. In the former, fungal mycelium forms a mat outside the root while in the

latter fungal hyphae dwell inside roots in intercellular spaces of cortex and forms VAM

(Vesicular-arbuscular mycorrhizae). Endomycorrhizae are found in several vascular plants while

ectomycorrhizae occur in several tree and shrub species in temperature regions.

Acclimatization

The gradual physiological adjustment to slowly changing new environmental conditions is known as

acclimatization. Most of the acclimatization change is biochemically based.

Phenotypic plasticity

The phenotypes show variations due to differences in the environmental conditions of the local

habitat. Such variations among individuals produced by the influence of the local conditions of the

habitat are known as phenotypic plasticity. It results in the formation of ecotypes.

Ecotype

Usually species having a wide range of distribution evolve genetically adapted local populations,

called ecotypes. Ecotypes differ from each other on the basis of morphological and physiological

characters. Although ecotypes of a species differ genetically, they are interfertile. Ecotypes are

commonly found among plants and sessile animals. The transition area between two ecotypes shows

a gradual change from one ecotype to the other largely due to interbreeding. It is called ecocline.

Ecophene or Ecads

Ecads are varied local populations with various morphological and physiological traits to suit

particular environment.

POPULATIONS

• Population has been defined differently in different field of study e.g., in Genetics population is a

group of interbreeding individuals of a species which are reproductively isolated from other such



groups.

• In ecology a population is a group of individuals of the same species inhabiting the same area

and functioning as a unit of biotic community. It is called local population or deme. The different

local population of a species is connected by dispersing individuals. A set of local populations

connected by dispersing individuals is called a metapopulation.

Origin & concept of single species population

• Species are group of populations, which can interbreed to give fertile offspring. Organisms

belonging to a given species rarely exist naturally as a single large population. It is usual for

species to exist as small interbreeding populations, called demes, small, isolated populations may

be important in speciation, as mutation, and selection may produce variations within the species.

• The wider distribution of organisms can be traced to its wide tolerance-limits. As the

environmental condition in force differs at different places, the organisms may evolve into

Ecotypes and Ecotypes into Biotypes. Subsequently, the biotype goes on to evolve into species.

Thus, from a common stock as represented by species A, species B and species C have evolved

and the environmental fluctuations are the causal factors. In a complex of biological systems,

there are several species populations, each in tune with its particular environment.

• Species differ in their environmental requirements. They also differ in respect to their tolerance

to environmental fluctuations. The species occur in several morphological forms in different

habitat conditions. Turesson conducted a series of experiments on variations of the plant along

maritime. He collected a group of 20 or more individuals of the same species from different areas

and planted them under identical environmental conditions in his experimental gardens. He noted

that several intergrading forms existed within the species which differed from one another in

morphological or physiological feature; he also noted that some of the features were unstable and

induced only the environmental factors where as others where permanent. Based on these studies

he proposed the following classes of morphological form within a species.

Ecads or Ecophene or Habitat forms

Ecotypes

Ecospecies

Coenospecies

• Ecads or Ecophenes: These are also called habitat forms, which are environmentally induced

variations. They belong to the same genetic stock or species and the variations in their

morphology (in shape, size, number and reproductive capacity) are induced by environmental

influences. The variations are not fixed, somatic and reversible. If one type of ecad is

transplanted into environment of another type of ecad the difference would disappear. It has been

observed that Euphorbia hirta plants growing in grasslands are prostrate and profusely branched

while the plants of the same species growing on the footpaths are compact, small leaved and

cushioned. When these forms are grown under identical habitat conditions the differences

disappear.

• Ecotypes: The term ecotypes was proposed by Turesson to the groupings of populations or

ecological races or subspecies of a species in relation to different environmental or habitat



conditions. These are interfertile forms of biotypes of a species which posses different genetic

composition or genotypes and arise due to mutations, hybridizations and isolation. Ecotype is the

product of genetic response of a population to a habitat. Usually, species having a wide range of

distribution evolve genetically adapted local populations, called ecotypes. Ecotypes are

commonly found among plants and sessile animals.

• Ecospecies: Commonly refers to subspecies of a plant, and ecospecies can have one or more

ecotypes which are interfertile but ecotypes of one ecospecies do not produce offspring when

crossed with the ecotypes of other ecospecies.

• Coenospecies: Different ecospecies, which can undergo occasional crossing but do not produce

viable offspring are collectively brought under coenospecies. In other words, populations

incapable of exchanging genes with other populations of the same species are referred to as

coenospecies.

Population Attributes

• In nature, we rarely find isolated, single individuals of any species; majority of them live in

groups in a well defined geographical area, share or compete for similar resources, potentially

interbreed and thus constitute a population.

• Although the term interbreeding implies sexual reproduction, a group of individuals resulting

from even asexual reproduction is also generally considered a population for the purpose of

ecological studies.

• All the cormorants in a wetland, rats in an abandoned dwelling, teakwood trees in a forest tract,

bacteria in a culture plate and lotus plants in a pond, are some examples of a population.

• Although an individual organism is the one that has to cope with a changed environment, it is at

the population level that natural selection operates to evolve the desired traits. Population

ecology is, therefore, an important area of ecology because it links ecology to population genetics

and evolution.

• A population has certain attributes that an individual organism does not. An individual may have

births and deaths, but a population has birth rates and death rates. In a population these rates

refer to per capita births and deaths, respectively.

• The rates, hence, are expressed is change in numbers (increase or decrease) with respect to

members of the population. Here is an example. If in a pond there are 20 lotus plants last year

and through reproduction 8 new plants are added, taking the current population to 28, we

calculate the birth rate as 8/20 = 0.4 offspring per lotus per year. If 4 individuals in a laboratory

population of 40 fruitflies died during a specified time interval, say a week, the death rate in the

population during that period is 4/40 = 0.1 individuals per fruit fly per week.

• Another attribute characteristic of a population is sex ratio. An individual is either a male or a

female but a population has a sex ratio (e.g., 60 per cent of the population are females and 40 per

cent males).

• A population at any given time is composed of individuals of different ages. If the age

distribution (per cent individuals of a given age or age group) is plotted for the population, the

resulting structure is called an age pyramid. For human population, the age pyramids generally

show age distribution of males and females in a combined diagram. The shape of the pyramids

reflects the growth status of the population - (1) whether it is growing, (2) stable or (3) declining.



Representation of age pyramids for human population

Age Pyramids

• The graphic representation of the proportions of different age groups in the population of any

organisms is called age pyramid. The pre-reproductive group is placed at the base, reproductive

in the middle and post reproductive group at the top. The age pyramids can be of three types–

Triangular age pyramid (Expanding): It indicates a high percentage of young individuals.

In rapidly growing young populations birth rate is high and population growth may be

exponential as in yeast, house fly, Paramecium etc. Under such conditions each successive

generation will be more numerous than the preceding ones and thus a triangular pyramid with

broad base will result.

Bell shaped age pyramid (Stable): In this case the pre-reproductive and reproductive age

groups becomes more or less equal in size while post-reproductive group; remains the

smallest. This results in bell shaped, structure of the pyramid. This type of age distribution

results in stable population.

Urn shaped age pyramid (Declining): It indicates a low percentage of young individuals. If

the birth rate is drastically reduced the pre-reproductive group dwindles in proportion to the

other two groups and it results in Urn shaped pyramid. Such a population shows negative

growth and decreases in size.

POPULATION DENSITY

• The size of the population tells us a lot about its status in the habitat. Whatever ecological

processes we wish to investigate in a population, be predator or the effect of a pesticide

application, we always evaluate them in terms of any change in the population size.

• The size, in nature, could be as low as <10 (Siberian cranes at Bharatpur wetlands in any year) or

go into millions (Chlamydomonas in a pond). Population size, more technically called

population density (designated as N), need not necessarily be measured in numbers only.

Although total number is generally the most appropriate measure of population density, it is in

some cases either meaningless or difficult to determine. In an area, if there are 200 Parthenium

plants but only a single huge banyan tree with a large canopy, stating that the population density

of banyan is low relative to that of Parthenium amounts to underestimating the enormous role of

the Banyan in that community. In such cases, the per cent cover or biomass is a more meaningful

measure of the population size. Total number is again not an easily adoptable measure if the

population is huge and counting is impossible or very time-consuming.

• Sometimes, for certain ecological investigations, there is no need to know the absolute

population densities; relative densities serve the purpose equally well. For instance, the number

Reproductive



of fish caught per trap is good enough measure of its total population density in the lake. We are

mostly obliged to estimate population sizes indirectly, without actually counting them or seeing

them. The tiger census in our national parks and tiger reserves is often based on pug marks and

fecal pellets.

Population Growth

• The size of a population for any species is not a static parameter. It keeps changing in time,

depending on various factors including food availability, predation pressure and reduces weather.

In fact, it is these changes in population density that give us some idea of what is happening to

the population – whether it is flourishing or declining.

• Whatever might be the ultimate reasons, the density of a population in a given habitat during a

given period, fluctuates due to changes in four basic processes, two of which (natality and

immigration) contribute an increase in population density and two (mortality and emigration) to

a decrease.

(i) Natality refers to the number of births during a given period in the population that are

added to the initial density.

(ii) Mortality is the number of deaths in the population during a given period.

(iii) Immigration is the number of individuals of the same species that have come into the

habitat from elsewhere during the time period under consideration.

(iv) Emigration is the number of individuals of the population who left the habitat and gone

elsewhere during the time period under consideration.

So, if N is the population density at time t, then its density at time t +1 is

Nt+1 = Nt + [(B + I) – (D + E)]



t

• From the above equation that population density will increase if the number of births plus the

number of immigrants (B + I) is more than the number of deaths plus the number of emigrants (D

+ E), otherwise it will decrease.

• Under normal conditions, births and deaths are the most important factors influencing population

density, the other two factors assuming importance only under special conditions. For instance,

if a new habitat is just being colonized, immigration may contribute more significantly to

population growth than birth rates.

Growth Models:

(i) Exponential growth: Resource (food and space) availability is obviously essential for the

unimpeded growth of a population. Ideally, when resources in the habitat are unlimited, each

species has the ability to realize fully its innate potential to grow in number, as Darwin observed

while developing his theory of natural selection. Then the population grows in an exponential or

geometric fashion. It in a population of size N, the birth rates (not total number but per capita

births) are represented as b and death rates (again, per capita death rates) as d, then the increase

or decrease in N during a unit time period t (dN/dt) will be

dN/dt = (b-d) N,

Let (b-d) = r then

dN/dt = rN

The r in this equation is called the ‘intrinsic rate of natural increase’ and is a very

important parameter chosen for assessing impacts of any biotic or abiotic factor on

population growth.

To give you some idea about the magnitude of r values, for the Norway rat the r is 0.015, and

for the flour beetle it is 0.12. In 1981, the r value for human population in India was 0.0205.

The above equation describes the exponential or geometric growth pattern of a population

and results in a J-shaped curve when we plot N in relation to time. If you are familiar with

basic calculus, you can derive the integral form of the exponential growth equation as

Nt = N0 ert, where

N = Population density after time t

N0 = Population density at time zero

r = intrinsic rate of natural increase

e = the base of natural logarithms (2.71828)



• Any species growing exponentially under unlimited resource conditions can reach

enormous population densities in a short time. Darwin showed how even. Population

growth curve a when responses are not limiting the growth, plot is exponential, b when

responses are limiting the growth, plot is logistic, K is carrying capacity a slow growing

animal like elephant could reach enormous numbers in the absence of checks.

(ii) Logistic growth: No population of any species in nature has its disposal unlimited resources

to permit exponential growth. This leads to competition between individuals for limited

resources. Eventually, the ‘fittest’ individual will survive and reproduce. The governments of

many countries have also realised this fact and introduced various restraints with a view to

limit human population growth.

• In nature, a given habitat has enough resources to support a maximum possible number,

beyond which no further growth is possible. Let us call this limit as nature’s carrying

capacity (K) for that species in that habitat.

• A population growing in a habitat with limited resources show initially a lag phase,

followed by phases of acceleration and deceleration and finally an asymptote, when the

population density reaches the carrying capacity. A plot of N in relation to time (t) results

in a sigmoid curve. This type of population growth is called Verhulst-Pearl Logistic

Growth and is described by the following equation:

K N

dN / dt rNK

Where N = Population density at time t

r = Intrinsic rate of natural increase, K = Carrying capacity

Since resources for growth for most animal populations are finite and become limiting sooner

or later, the logistic growth model is considered a more realistic one.

Life History Variation

• Populations evolve to maximise their reproductive fitness, also called Darwinian fitness (high r

value), in the habitat in which they live. Under a particular set of selection pressures, organisms

evolve towards the most efficient reproductive strategy. Some organisms breed only once in their

lifetime (Pacific salmon fish, bamboo) while others breed many times during their lifetime (most

birds and mammals).

• Some produce a large number of small-sized offspring (Oysters, pelagic fishes) while others

produce a small number of large-sized offspring (birds, mammals).

• Ecologists suggest that life history traits of organisms have evolved in relation to the constraints

imposed by the abiotic and biotic components of the habitat in which they live. Evolution of life

history traits in different species is currently an important area of research being conducted by

ecologists.


• There is no natural habitat on earth that is inhabited just by a single species such a situation is

even inconceivable. For any species, the minimal requirement is one more species on which it

can feed. Even a plant species, which makes its own food, cannot survive alone; it needs soil

microbes to break down the organic matter in soil and return the inorganic nutrients for

absorption. And then, how will the plant manage pollination without an animal agent?



• It is obvious that in nature, animals, plants and microbes do not and cannot live in isolation but

interact in various ways to form a biological community. Even in minimal communities, many

interactive linkages exist, although all may not be readily apparent.

• Interspecific interactions arise from the interaction of populations of two different species. They

could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or

both. Assigning a ‘+’ sign for beneficial interaction, ‘-’ sign for detrimental and 0 for neutral

interaction, let us look at all the possible outcomes of interspecific interactions.


• Both the species benefit in mutualism and both lose in competition in their interactions with each

other.

• In both Parasitism and Predation only one species benefits (parasite and predator, respectively)

and the interaction is detrimental to the other species (host and prey, respectively).

• The interaction where one species is benefitted and the other is neither benefitted nor harmed is

called commensalism.

• In amensalism on the other hand one species is harmed whereas the other is unaffected.

• Predation, parasitism and commensalism share a common characteristic– the interacting species

live closely together.

(i) Predation:

• Predation is nature’s way of transferring to higher trophic levels the energy fixed by plants.

When we think of a predator and its prey, most probably it is the tiger and the deer that

readily comes to our mind, but a sparrow eating any seed is no less a predator. Although

animals eating plants are categorised separately as herbivores, they are, in a broad ecological

context, not very different from predators.

• Besides acting as ‘conduits’ for energy transfer across trophic levels, predators play other

important roles. They keep prey populations under control. But for predators, prey species

could achieve very high population densities and cause ecosystem instability.

• When certain exotic species are introduced into a geographical area, they become invasive

and start spreading fast because the invaded land does not have its natural predators. The

prickly pear cactus introduced into Australia in the early 1920’s caused havoc by spreading

rapidly into millions of hectares of rangeland. Finally, the invasive cactus was brought under

control only after a cactus-feeding predator (a moth) from its natural habitat was introduced

into the country.

Species A

Species B

Name of Interaction

+ + Mutualism

– – Competition

+

–

Predation

+ – Parasitism

+

0

Commensalism

– 0 Amensalism



• Biological control methods adopted in agricultural pest control are based on the ability of the

predator to regulate prey population. Predators also help in maintaining species diversity in a

community, by reducing the intensity of competition among competing prey species.

Example:

In the rocky intertidal communities of the American Pacific Coast the starfish Pisaster is an

important predator. In a field experiment, when all the starfish were removed from an enclosed

intertidal area, more than 10 species of invertebrates became extinct within a year, because of inter-

specific competition.

• If a predator is too efficient and overexploits its prey, then the prey might become extinct and

following it, the predator will also become extinct for lack of food. This is the reason why

predators in nature are ‘prudent’.

• Prey species have evolved various defenses to lessen the impact of predation. Some species

of insects and frogs are cryptically-coloured (camouflaged) to avoid being detected easily by

the predator.

• Some are poisonous and therefore avoided by the predators. The Monarch butterfly is highly

distasteful to tis predator (bird) because of a special chemical present in its body.

Interestingly, the butterfly acquires this chemical during its caterpillar stage by feeding on a

poisonous weed.

• For plants, herbivores are the predators. Nearly 25 per cent of all insects are known to be

phytophagous (feeding on plant sap and other parts of plants). The problem is particularly

severe for plants because, unlike animals, they cannot run away from their predators. Plants

therefore have evolved an astonishing variety of morphological and chemical defences

against herbivores.

• Thorns (Acacia, Cactus) are the most common morphological means of defence. Many plants

produce and store chemicals that make the herbivore sick when they are eaten, inhibit feeding

or digestion, disrupt its reproduction or even kill it. Weed Calotropis growing in abandoned

fields produces highly poisonous cardiac glycosides and that is why you never see any cattle

or goats browsing on this plant.

• A wide variety of chemical substances that we extract from plants on a commercial scale

(nicotine, caffeine, quinine, strychnine, opium, etc.,) are produced by them actually as

defences against grazers and browsers.

(ii) Competition:

• When Darwin spoke of the struggle for existence and survival of the fittest in nature, he was

convinced that interspecific competition is a potent force in organic evolution.

• It is generally believed that competition occurs when closely related species compete for the

same resources that are limiting, but this is not entirely true. Firstly, totally unrelated species

could also compete for the same resource. For instance, in some shallow South American

lakes visiting flamingoes and resident fishes compete for their common food, the zooplankton

in the lake. Secondly, resources need not be limiting for competition to occur; in

interference competition, the feeding efficiency of one species might be reduced due to the

interfering and inhibitory presence of the other species, even if resources (food and space) are

abundant.



• Therefore, competition is best defined as a process in which the fitness of one species

(measured in terms of its ‘r’ the intrinsic rate of increase) is significantly lower in the

presence of another species.

• It is relatively easy to demonstrate in laboratory experiments, as Gause and other

experimental ecologists did, when resources are limited the competitively superior species

will eventually eliminate the other species, but evidence for such competitive exclusion

occurring in nature is not always conclusive. Strong and persuasive circumstantial evidence

does exist however in some cases. The Abingdon tortoise in Galapagos Islands became

extinct within a decade after goats were introduced on the island, apparently due to the

greater browsing efficiency of the goats.

• Another evidence for the occurrence of competition in nature comes from what is called

‘competitive release’. A species, whose distribution is restricted to a small geographical area

because of the presence of a competitively superior species, is found to expand its

distributional range dramatically when the competing species is experimentally removed.

• Connell’s elegant field experiments showed that on the rocky sea coasts of Scotland, the

larger and competitively superior barnacle Balanus dominates the intertidal area, and

excludes the smaller barnacle Chathamalus from that zone. In general, herbivores and plants

appear to be more adversely affected by competition than carnivores.

• Gause’s ‘Competitive Exclusion Principle’ states that two closely related species competing

for the same resources cannot co-exist indefinitely and the competitively inferior one will be

eliminated eventually. This may be true if resources are limiting, but not otherwise.

• More recent studies do not support such gross generalisations about competition. While they

do not rule out the occurrence of interspecific competition in nature, they point out that

species facing competition might evolve mechanisms that promote co-existence rather than

exclusion. One such mechanism is ‘resource partitioning’. If two species compete for the

same resource, they could avoid competition by choosing, for instance, different times for

feeding or different foraging patterns.

• MacArthur showed that five closely related species of warblers living on the same tree were

able to avoid competition and co-exist due to behavioral differences in their foraging

activities.

(iii) Parasitism:

• Considering that the parasitic mode of life ensures free lodging and meals, it is not surprising

that parasitism has evolved in so many taxonomic groups from plants to higher vertebrates.

• Many parasites have evolved to be host-specific (they can parasitise only a single species of

host) in such a way that both host and the parasite tend to co-evolve; that is, if the host

evolves special mechanisms for rejecting or resisting the parasite, the parasite has to evolve

mechanisms to counteract and neutralise them, in order to be successful with the same host

species.

• In accordance with their life styles, parasites evolved special adaptations such as the loss of

unnecessary sense organs, presence of adhesive organs or suckers to cling on to the host, loss

of digestive system and high reproductive capacity.



• The life cycles of parasites are often complex, involving one or two intermediate hosts or

vectors to facilitate parasitation of its primary host. The human liver fluke (a trematode

parasite) depends on two intermediate hosts (a snail and a fish) to complete its life cycle. The

malarial parasite needs a vector (mosquito) to spread to other hosts.

• Majority of the parasites harms the host; they may reduce the survival, growth and

reproduction of the host and reduce its population density. They might render the host more

vulnerable to predation by making it physically weak.

• Parasites that feed on the external surface of the host organism are called ectoparasites. The

most familiar examples of this group are the lice on humans and ticks on dogs. Many marine

fish are infested with ectoparasitic copepods. Cuscuta, a parasitic plant that is commonly

found growing on hedge plants, has lost its chlorophyll and leaves in the course of evolution.

It derives its nutrition from the host plant which it parasitises. The female mosquito is not

considered a parasite, although it needs our blood for reproduction.

• In contrast, endoparasites are those that live inside the host body at different sites (liver,

kidney, lungs, red blood cells, etc.). The life cycles of endoparasites are more complex

because of their extreme specialisation. Their morphological and anatomical features are

greatly simplified while emphasising their reproductive potential.

• Brood parasitism in birds is fascinating examples of parasitism in which the parasitic bird

lays its eggs in the nest of its host and lets the host incubate them. During the course of

evolution, the eggs of the parasitic bird have evolved to resemble the host’s egg in size and

colour to reduce the chances of the host bird detecting the foreign eggs and ejecting them

from the nest.

(iv) Commensalism:

• This is the interaction in which one species benefits and the other is neither harmed nor

benefited. For example, an orchid growing as an epiphyte on a mango branch or barnacles

growing on the back of a whale, benefit while neither the mango tree nor the whale derives

any apparent benefit.

• The cattle egret and grazing cattle in close association, a sight you are most likely to catch if

you live in farmed rural areas, is a classic example of commensalism. The egrets always

forage close to where the cattle are grazing because the cattle, as they move, stir up and flush

out from the vegetation insects that otherwise might be difficult for the egrets to find and

catch. Another example of commensalism is the interaction between sea anemone that has

stinging tentacles and the clown fish. The fish gets protection from predators which stay

away from the stinging tentacles. The anemone does not appear to derive any benefit by

hosting the clown fish.

(1) (2)

Mutual relationship between fig tree and wasp: (1) Fig flower is pollinated by wasp; (2)

Wasp laying eggs in a fig fruit lives among them.



(v) Mutualism:

• This interaction confers benefits on both the interacting species. Lichens represent an

intimate mutualistic relationship between a fungus and photosynthesising algae or

cyanobacteria. Similarly, the mycorrhizae are associations between fungi and the roots of

higher plants. The fungi help the plant in the absorption of essential nutrients from the soil

while the plant in turn provides the fungi with energy-yielding carbohydrates.

• The most spectacular and evolutionarily fascinating examples of mutualism are found in

plant-animal relationships. Plants need the help of animals for pollinating their flowers and

dispersing their seeds. Animals obviously have to be paid ‘fees’ for the services that plants

expect from them. Plants offer rewards or fees in the form of pollen and nectar for pollinators

and juicy and nutritious fruits for seed dispersers.

• But the mutually beneficial system should also be safeguarded against ‘cheaters’, for

example, animals that try to steal nectar without aiding in pollination. These plant-animal

interactions often involve co-evolution of the mutualists, that is, the evolutions of the flower

and its pollinator species are tightly linked with one another. In many species of fig trees,

there is a tight one-to-one relationship with the pollinator species of wasp. It means that a

given fig species can be pollinated only by its ‘partner’ wasp species and no other species.

The female wasp uses the fruit not only as an oviposition (egg-laying) site but uses the

developing seeds within the fruit for nourishing its larvae.

• The wasp pollinates the fig inflorescence while

searching for suitable egg-laying sites. In return

for the favour of pollination the fig offers the

wasp some of its developing seeds, as food for

the developing wasp larvae.

Showing bee a pollinator

on orchid flower

• Orchids show a bewildering diversity of floral patterns many of which have evolved to attract

the right pollinator insect (bees and bumblebees) and ensure guaranteed pollination by it.

• Not all orchids offer rewards. The Mediterranean orchid Ophrys employs ‘sexual deceit’ to

get pollination done by a species of bee. One petal of its flower bears an uncanny

resemblance to the female of the bee in size, colour and markings. The male bee is attracted

to what it perceives as a female, ‘pseudocopulates’ with the flower, and during that process

is dusted with pollen from the flower. When this same bee ‘pseudocopulates’ with another

flower, it transfers pollen to it and thus, pollinates the flower. This is co-evolution. If the

female bee’s colour patterns change even slightly for any reason during evolution, pollination

success will be reduced unless the orchid flower co-evolves to maintain the resemblance of

its petal to the female bee.

————



EXERCISE # LEVEL–I (CLASS WORK)

1. The ‘niche’ of a species is meant for

(1) Habitat and specific functions of a species

(2) Specific place where an organism lives

(3) Specific species function and its competitive power

(4) Both (1) and (3)

2. Two opposite forces operate in the growth and development of every population. One of them is

related to the ability to reproduce at a given rate. The force opposite to it is called

(1) Fecundity (2) Environmental resistance

(3) Biotic control (4) Mortality

3. The formula for exponential population growth is

(1) dN/dt = rN (2) dt/dN = rN (3) dN/rN = dt (4) rN/dN = dt

4. Certain characteristic demographic features of developing countries are

(1) High fertility, low or rapidly falling mortality rate, rapid population growth and a very young

age distribution

(2) High fertility, high density, rapidly rising mortality rate and a very young age distribution

(3) High infant mortality, low fertility, uneven population growth a very young age distribution

(4) High mortality, high density, uneven population growth and a very old age distribution

5. Geometric representation of age structure is a characteristic of

(1) Population (2) Landscape (3) Ecosystem (4) Biotic community

6. The population of an insect species shows an explosive increase in numbers during rainy season

followed by an eruptive fall at the end of the season. What does this show?

(1) The plants on which the insects feed on mature and die at the end of the rainy season

(2) Its population growth curve is of J-type

(3) The population of its predators increases enormously

(4) Its population growth curve is of S-type or sigmoid type

7. Which type of association is found in between entomophilous flower and pollinating agent?

(1) Amensalism (2) Commensalism (3) Cooperation (4) Co-evolution

8. Unrestricted reproductive capacity in a population is called as

(1) Biotic potential (2) Fertility (3) Carrying capacity (4) Birth rate

9. In bacteria, fungi and lower plants, various kind of thick walled spores, are formed which help

them to survive under unfavourable conditions, and these can be categorized as to

(1) Migrate (2) Suspend (3) Regulate (4) Conform

10. Niche overlap indicates

(1) Mutualism between two species

(2) Active co-operation between two species

(3) Two different parasites on the same host

(4) Sharing of one of more resources between the two species

11. Which one of the following is one of the characteristics of a biological community?

(1) Sex-ratio (2) Stratification (3) Natality (4) Mortality



12. Study the four statement (1-4) given below and select the two correct ones out of them

(1) A lion eating a deer and sparrow feeding on worms are ecologically similar in being

consumers

(2) Predator star fish Pisaster helps in maintaining species diversity of some invertebrates

(3) Predators ultimately lead to the increase of prey species

(4) Production of chemicals such as nicotine, strychnine by the plants is metabolic disorders

The two correct statements are

(1) (1) and (2) (2) (2) and (3) (3) (3) and (4) (4) (1) and (4)

13. Which one of the following is most appropriately defined?

(1) Host is an organism which provides food to another organism

(2) Amensalism is a relationship in which one species is benefited whereas the other is

unaffected

(3) Predator is an organism that catches and kills other organism for food

(4) Parasite is an organism that catches and kills other organism for food

14. Change in population size equation with prolonged exponential phase can be converted into

logistic growth equation by multiplying it with

(1) K

N (2)

K N

K

(3)

K

K N (4)

1

N K

15. Ecological relationship in which one individual is benefited and another one neither benefited nor

harmed is called is

(1) Amensalism (2) Commensalism (3) Protoco-operation (4) Mutualism

16. Ecophenes of habitat forms are also called as

(1) Ecads (2) Ecotypes (3) Ecospecies (4) Ecotones

17. Theoretical birth rate under ideal conditions of environment is called as

(1) Ecological natality (2) Realised natality (3) Burst size (4) Reproductive potential

18. Organisms occupying similar ecological niche but different geographical areas of distribution are

called as

(1) Edge species (2) Ecological equivalents

(3) Ecoclines (4) Inquilines

19 Population evolve to maximize their reproductive fitness also called Darwinian fitness with

(1) High r value (2) Low r value (3) High K value (4) High K N

K

value

20. Altitude sickness is managed by the body by

(1) Decreasing RBC production

(2) Increasing fat oxidation

(3) Decreasing binding capacity of hemoglobin

(4) Decreasing breathing rate

21. Desert lizards deal with the high and low temperature of their habitat by

(1) Physiological means (2) Behavioural means

(3) Suspending their activities (4) Migrating

22. Select incorrect statement

(1) Organisms living in oceans, lakes and rivers do not face any water related problems

(2) Productivity and distribution of plants is dependent on water

(3) The levels of thermal tolerance of different species determine to a large extent their

geographical distribution



(4) Foraging, reproductive and migratory activities of some animals are dependent on seasonal

variation in light

23. Select incorrect statement regarding different population attributes

(1) Natural selection operates at population level

(2) Size of the population tells a lot about its status in the habitat

(3) In age pyramids age distribution of male and females are shown in separates diagrams

(4) Population is a group of individuals multiplying by sexual and asexual reproduction

24. Predation, parasitism and commensalism share a common characteristic i.e,

(1) Both the interacting species are benefited

(2) Interacting species live closely together

(3) One of the species is benefited while other is harmed

(4) Both the species belong to same taxonomic group

25. Salt concentration for inland water measured as parts per thousand is

(1) 5% (2) 30-35% (3) 100% (4) 100%

26. Which of the following is incorrect w.r.t. competition?

(1) Resources need not be limiting for competition to occur

(2) Competitive species may evolve mechanism that promote their co-existence

(3) Connel’s field experiment is an example of competitive release

(4) Only closely related species can show competition

27. How many key environmental elements lead to so much variation in the physical and chemical

conditions of different habitats? Amongst these which is the most ecologically relevant factor?

(1) Three, water (2) Four, Temperature (3) Four, Water (4) Three, Temperature

28. The salt concentration (measured as salinity in parts per thousand) in sea water as

(1) 30–35% (2) 5% (3) 5 – 10% (4) 100%

29. Desert Lizard show ______ means to maintain body _______.

(1) Physiological, temperature (2) Behavioural, osmolarity

(3) Behavioural, temperature (4) Physiological, osmolarity

30. Which of the following factor will contribute more significantly to population growth in a new

habitat being colonized?

(1) Natality (2) Mortality (3) Immigration (4) Emigration



LEVEL–II (HOME WORK)

1. A given habitat has enough resources to support a maximum possible number, beyond which no

further growth is possible, this limit is _______ and represented as ________.

(1) Intrinsic rate of natural increase, r (2) Biotic potential, r

(3) Carrying capacity, K (4) Environmental resistance, K N

K

2. A field experiment performed at American Pacific Coast involving removal of starfish explains

the significance of

(1) Mutualism (2) Competition (3) Predation (4) Parasitism

3. The feeding efficiency of one species might be reduced due to the inhibitory presence of the other

species even if resources are abundant. This explains

(1) Competitive exclusion (2) Interference competition

(3) Competitive release (4) Resource partitioning

4. Immigration is different from emigration in

(1) Having outward movement of individuals (2) Decreasing the size of population

(3) Increasing the size of population (4) Survival with better food and shelter conditions

5. Predators are different from parasites as

(1) they feed on dead organisms (2) they have poor means of dispersal

(3) they have high biotic potential (4) they help to maintain species diversity

6. Choose odd one w.r.t. population interactions

(1) Cattle egret and Cattle (2) Orchid and Mango

(3) Sea anemone and Clown fish (4) Fig flower and Wasp

7. Parasites evolved special adaptations in accordance with their life styles. Choose odd one out

w.r.t. these adaptations.

(1) Low reproductive capacity

(2) Simple life cycle and complex morphological, anatomical features

(3) Loss of unnecessary sense organs

(4) Loss of digestive system

8. Which of the following is very important parameter chosen for assessing impacts of any biotic or

abiotic factor on population growth?

(1) Carrying capacity (2) Environmental resistance

(3) Intrinsic rate of natural increase (4) More than one option is correct

9. Dormant stage in the development of an organism which can occur both in summer and winter

season is ______ and shown by _______.

(1) Hibernation, animals only (2) Diapause, Zooplanktons

(3) Aestivation, Ectotherms (4) Diapause, plants only

10. How many basic processes control the population density in a given habitat during a given time

and amongst these, mention the two important factors controlling population density under

normal conditions respectively.

(1) Four I, B (2) Three, B, D (3) Four, B, D (4) Three, I, B

11. Ecology is basically concerned with ________ levels of biological organizations

(1) two (2) three (3) four (4) one

12. Warm blooded animals living in colder areas have shorter extremities than the animals of warmer



areas is explained by

(1) Allen’s rule (2) Bergman’s rule (3) Gloger’s rule (4) Rensch’s rule

13. Negative growth is represented by which of the following age pyramid graph?

(1) Urn shape (2) Bell shape (3) Triangular shape (4) Both (1) and (2)

14. The relationship between ox pecker and rhinoceros is

(1) +, 0 (2) +, + (3) 0, – (4) 0, +

15. Verhulst – Pearl logistic population growth is represented by

(1) dN

rNdt

(2) dN K N

rNdt K

(3) Nt = N0e

rt (4) Nt = N0 + I + B – E – D

16. Select the incorrect statement w.r.t. predation

(1) Predators are prudent

(2) Predation results into interspecific competition

(3) Predators help in maintaining species diversity

(4) Predators can reduce the intensity of competition among competing prey species

17. The tiger census in our national parks and tiger reserves in often based on

(1) Direct methods (2) Pug marks

(3) Fecal pellets (4) More than one option is correct

18. Study the four statements (1 – 4) given below and select the two correct ones out of them.

(1) Gause’s Competitive Exclusion Principle is true if resources are unlimiting

(2) Sea anemone is commensal when it interacts with clown fish

(3) If resource is limiting the population growth then plot will be logistic

(4) Under unfavourable conditions many zooplankton species in lakes and ponds are known to

enter diapause

(1) (3) & (4) (2) (2) & (3) (3) (1) & (3) (4) (1) & (4)

19. The most ecologically relevant environmental factor is

(1) Water (2) Temperature (3) Light (4) Soil

20. Mark the incorrect match

(1) Oysters, pelagic fishes – Small sized offspring

(2) Pacific salmon fish, bamboo – Breed many times in life time

(3) Birds, mammals – Large sized offspring

(4) Birds, mammals – Breed many times in life time

21. Diapause is a stage of suspended development found in

(1) Zooplanktons (2) Birds (3) Bats (4) Phytoplanktons

22. Pisaster is an important _______ in the rocky intertidal communities of American Pacific Coast.

(1) Predator (2) Parasitic animal (3) Parasitic plant (4) Epiphyte

23. An orchid growing as an epiphyte on a mango branch shows what kind of population interaction?

(1) Amensalism (2) Commensalism (3) Mutualism (4) Proto co-operation

24. Read the following statements and select the correct option w.r.t. population attributes.

(1) Population density is necessarily measured in numbers

(2) Tiger census is often based on pug marks and fecal pellets

(3) Biomass is a not a meaningful measure to known population size

(4) Size of a population for any species is not a static parameter

(1) 1, 2 (2) 2, 3 (3) 3, 4 (4) 2, 4



25. Kangaroo rat in North American desert

(1) is capable of meeting water requirement through its internal fat oxidation

(2) has the ability to concentrate its urine

(3) manage the body temperature by sweating

(4) more than one option is correct

26. Connell’s elegant field experiment explains

(1) Exclusion principle (2) Co-existence

(3) Resource partitioning (4) Competitive release

27. Many fishes thrive in Antarctic waters where the temperature is always below zero. In these

animals, ice formation is prevented due to presence of

(1) Ice nucleating proteins (2) Glycerol and ice nucleating proteins

(3) glycerol and anti-freeze proteins (4) Sorbitol and ice nucleating proteins

28. Competition for food, light and space is most severe between two

(1) Distantly related species growing in different habitat

(2) Distantly related species growing in the same habitat

(3) Closely related species growing in different habitat

(4) Closely related species growing in the same area

29. Transition zone between two communities is called

(1) Ecocline (2) Ecotone (3) Buffer zone (4) Thermocline

30. ‘Edge effect’ refers to

(1) Occurrence of ecophenes and ecotypes in a community

(2) Low diversity of organisms in ecotone

(3) High diversity of organisms in ecotone

(4) Defence of territories by organisms

31. Which of the following is most appropriately defined?

(1) Commensalism is a relationship in which one species is benefited and the other is neither

benefited nor harmed

(2) Parasite is an organism which always lives inside the body of other organism and may kill it

(3) Competition is defined as a process in which the fitness of one species is significantly higher

in the presence of another species

(4) Mutualism is a relationship in which one species is benefited where as the other is unaffected

32. A predator

(1) Is too efficient to overexploit its prey

(2) Helps in maintaining species diversity by increasing the intensity of competition among prey

species

(3) Acts as conduits for energy transfer across trophic levels

(4) Shows (+, +) interaction with its prey

33. Select the correct statement w.r.t. adaptations

(1) Desert lizards bask in the sun and absorb heat when their body temperature drops below

comfort zone

(2) To stop experiencing altitude sickness, the body compensates low oxygen availability by

increasing binding affinity of hemoglobin

(3) Mammals of colder climate generally have larger ears and limbs to minimize heat loss

(4) Many desert plants have thin cuticle on their leaf surface and have their stomata arranged on

upper surface to minimize water loss



ASSERTION & REASON QUESTIONS (CLASS WORK)


(1) If both Assertion & Reason are true and the reason is the correct explanation of the

assertion, then mark (1)

(2) If both Assertion & Reason are true but the reason is not the correct explanation of the


(3) If Assertion is true statement but Reason is false, then mark (3)

(4) If both Assertion and Reason are false statements, then mark (4)

1. A: Daphnia populations in a water body, at different seasons of a year showed marked

variations in their body morphology. [Guj CET]

R: Cyclomorphosis in some planktonic organisms is influenced by the variations in

temperatures prevailing in their water bodies at different seasons.

2. A : Predation is an interspecific interaction with a feeding strategy [EAMCET]

R: Predator and their prey maintain fairly stable population through time and rarely one

population become abundant or scarce.

3. A: Species are groups of potentially interbreeding natural populations that are isolated from

other such groups.

R: Reproductive isolation brings about distinctive morphological characters. [EAMCET]

4. A: Some organisms can maintain internal homeostasis by means of physiological processes

and are called ‘Regulates’.

R: ‘Regulates’ can maintain internal homeostasis only upto a limit of stressful conditions

5. A: Population ecology is a link of ecology to population genetics and evolution.

R: Natural selection operates at population level to evolve the desired traits.

6. A: Under unlimited resource condition a population can show an exponential growth curve.

R: A maximum possible number of individuals can always be supported when enough

resources are available.

7. A: Insects contribute maximum in total diversity of animals.

R: Angiosperms and insects are coevolved to perform a plant-pollinator interaction.

8. A: Ecology is interaction between abiotic and biotic factors, and also among biotic factors.

R: Ecology is basically concerned with four levels of biological organization.

9. A: At the organismic level ecology is mainly physiological ecology.

R: At organismic level ecology is in terms of adaptation for survival and reproduction.

10. A: Mango tree cannot and do not grow in temperate area.

R: Temperature is the most ecologically relevant environmental factor.



11. A: There has been a growing concern about the gradually increasing overall global

temperatures

R: The level of thermal tolerance of different species determines their geographical

distribution

12. A: Aquatic life does not guarantee freedom from water stress.

R: For aquatic organisms the quality i.e, chemical composition and pH of water become

important.

13. A: Small animals are not found in colder climate.

R: Heat loss or heat gain is a function of surface area.

14. A: Adaptations are important for survival of organism.

R: Adaptations are genetically fixed.

15. A: At high altitude, altitude sickness is experienced.

R: At high altitude atmospheric pressure is low.

16. A: Logistic growth model is considered as more realistic one.

R: Resource for growth in nature is finite.

17. A: Different organisms shows different life-history trait.

R: Abiotic and biotic factors impose constrain on life history trait.




1. Cuscuta is an example of: [AIPMT 2012]

(1) Predation (2) Endoparasitism (3) Ectoparasitism (4) Brood parasitism

2. People who have migrated from the planes to an area adjoining Rohtang Pass about six

months back: [AIPMT 2012]

(1) Suffer from altitude sickness with symptoms like nausea, fatigue, etc.

(2) Have the usual RBC count but their haemoglobin has very high binding affinity to O2

(3) Have more RBCs and their haemoglobin has a lower binding affinity to O2

(4) Are not physically fit to play games like football

3. Which one of the following microbes forms symbiotic association with plants and helps them

in their nutrition [AIPMT 2012]

(1) Glomus (2) Trichoderma (3) Azotobacter (4) Aspergillus

4. The basic unit of study in Ecology is [DUMET 2011]

(1) population (2) organism (3) community (4) species

5. 5th

June is celebrate as [OJEE 2011]

(1) water day (2) world environment day

(3) conservation day (4) world earth day

6. The study of the relation of an organism with its environment is called [J&K CET 2011]

(1) Synecology (2) Bionomics (3) Autoecology (4) Herpetology

7. The soil with poorest water holding capacity is [UP CPMT 2011]

(1) clay (2) loam (3) sandy (4) None of these

8. Pedology refers to study of [J&K CET 2011]

(1) soil (2) water (3) population (4) Fossils

9. The growth rate of a population stabilizes after [EAMCET 2011]

(1) logarithmic phase (2) stationary phase

(3) carrying capacity (4) negative acceleration phase

10. Match the following columns and choose the correct combination from the given option

Column I Column II

A. Mutualism 1. Ticks on dogs

B. Commensalism 2. Balanus and Chathalamus

C. Parasitism 3. Sparrow and any seed

D. Competition 4. Epiphyte on a mango branch

E. Predation 5. Ophrys and Colpa

[Kerala CEE 2011]

(1) A – 1, B – 5, C – 4, D – 3, E – 2 (2) A – 2, B – 1, C – 5, D – 4, E – 3

(3) A – 3, B – 2, C – 1, D – 5, E – 4 (4) A – 5, B – 4, C – 1, D – 2, E – 3

11. Exponential growth in plants can be expressed as [Kerala CEE 2011]

(1) Lt = L0 + rt (2) Le = Ltrt (3) W1 = W0ert (4) W1 = W0ert

(e) W1 = W0 + ert



12. The term ‘Niche’ was first used by [UP CPMT 2011]

(1) Clements (2) Grinnel (3) Warming (4) Odum

13. An interaction favourable to both population, but not obligatory to either is [UP CPMT 2011]

(1) proto-cooperation (2) mutualism (3) commensalisms (4) parasite

14. The most important factor which determined the increase in human population in India

during the 20th

century was [DUMET 2011]

(1) Natality (2) Mortality (3) Immigration (4) Emigration

15. A population growing in a habitat with limited resources shows four phase of growth in the

following sequence [DUMET 2011]

(1) Acceleration – Deceleration – lag phase – Asymptote

(2) Asymptote – Acceleration – Deceleration – Lag phase

(3) Lag-phase – Acceleration – Deceleration – Asymptote

(4) Acceleration – lag phase – Deceleration – Asymptote

16. Sigmoid growth curve is represented by [DUMET 2011]

(1) dN/ dt = rN (2) dN / dt = rN (K – N/K)

(3) Nt = No + B + I-D-E (4) dN/dt = 1 – N/K

17. The age of pyramid with broad base indicates [DUMET 2011]

(1) high percentage of young individuals (2) low percentage of young individuals

(3) high percentage of old individuals (4) low percentage of old individual

18. Hydrophytes are characterized by [OJEE 2011]

(1) presence of sclerenchyma (2) presence of aerenchyma

(3) absence of aerenchyma (4) presence of root nodules

19. In a population, unrestricted reproductive capacity is called [WB JEE 2011]

(1) biotic potential (2) fertility (3) carrying capacity (4) birth rate

20. Maximum survival and reproductive capacity shown by a population under optimal

environmental conditions is called [J&K CET 2011]

(1) carrying capacity (2) natality (3) biotic potential (4) vitality

21. The plants that grow on saline soils with high concentration of NaCl2, MgSO4 and MgCl2 are

called [Kerala CEE 2011]

(1) succulents (2) mesophytes (3) xerophytes (4) halophytes

22. There are two optional ways of exploitation. One way is parasitism. Which is the other one?

(1) Antibiosis (2) Competition [Guj CET 2011]

(3) Predation (4) Commensalism

23. Plants grown on sandy soil, are grouped under [OJEE 2010]

(1) lithophytes (2) psammophytes (3) hydrophytes (4) xerophytes

24. Barnacles growing on the back of whale is an example for [Kerala CEE 2010]

(1) mutualism (2) commensalism (3) parasitism (4) amensalism

(e) predation



25. The formula of growth rate for population in a given time is [Kerala CEE 2010]

(1) dt/dN = rN (2) dt/rN = dN (3) rN/dN = dt (4) dN/dt = rN

26. The association of animals when both partners are benefited is [OJEE 2010]

(1) commensalism (2) amensalism (3) mutualism (4) parasitism

27. Which one is the edaphic factor in biosphere? [J&K CET 2009]

(1) Light (2) Temperature (3) Water (4) Soil

28. Humus layer in soil composed of dead fresh organic matter called [UP CPMT 2009]

(1) litter (2) duff (3) real humus (4) compost

29. Halophytes are [AMU 2009]

(1) fire-resistant (2) cold-resistant (3) salt-resistant (4) sand-loving

30. Reproductive isolation between segments of a single population is termed as [DUMET 2009]

(1) sympatry (2) allopatry

(3) population divergence (4) disruptive divergence

31. The growth of a population without limit at its maximal rate and also that, rates of

immigration and emigration are equal, then it is called [EAMCET 2009]

(1) carrying capacity (2) biotic potential (3) positive growth (4) negative growth

32. Ratio between mortality and natality is called [J&K CET 2009]

(1) population ratio (2) vital index (3) density coefficient (4) census ratio

33. Genetically adapted population to a particular habitat is called [J&K CET 2009]

(1) ecotone (2) ecotype (3) biome (4) niche

34. The species of plants that play a vital role in controlling the relative abundance of the species

in a community are called [J&K CET 2009]

(1) edge species (2) keystone species (3) pioneer species (4) seral species

35. Phenomenal and rapid increase of population in a short period is called [J&K CET 2009]

(1) natural increase (2) population growth

(3) population explosion (4) None of these

36. The interaction of species with the environment is called as [DUMET 2008]

(1) community (2) environment (3) ecosystem (4) autecology

37. The soil, which is transported by wind is known as [UP CPMT 2008]

(1) colluvial (2) eolian (3) alluvial (4) glacial

38. The size of the clay particle is less than [DUMET 2008]

(1) 0.02 mm (2) 0.002 mm (3) 0.2 mm (4) 2.0 mm

39. What is true about the isolated small tribal population? [CBSE AIPMT 2008]

(1) There is a decline in population as boys marry girls only from their own tribe

(2) Hereditary diseases like colour blindness do not spread in the isolated population

(3) Wrestlers who develop strong body muscle in their life time pass this character on to their

progency

(4) There is no change in population size as they have a large gene pool



40. July 11th

is observed as [AIIMS 2008]

(1) World population day (2) No tobacco day

(3) World environment day (4) World health day

41. Small fish get stuck near the bottom of a shark and derives its nutrition from it. This kind of

association is called as [UP CPMT 2008]

(1) antibiosis (2) commensalism (3) predation (4) parasitism

42. A high density of tiger population in an area can result in [AMU 2008]

(1) predation (2) interspecific competition

(3) intraspecific competition (4) proto cooperation

43. Two species occupying same or overlapping area are called as [BHU 2008]

(1) sympatric (2) allopatric (3) parapatric (4) ring species

44. The niche of a population is defined as [Punjab PMET 2008]

(1) set of condition that interacts (2) place where it lives

(3) set of conditions and resources it uses (4) geographical area that is covers

45. In commensalism [Panjab PMET 2008]

(1) both partners are harmed (2) weaker partner is benefited

(3) both partners and benefited (4) None of the partners is benefited

46. What is a keystone species? [DUMET 2008]

(1) A species which adds upto only a small proportion of the total biomass of a community,

yet has huge impact on the community’s organization and survival

(2) A common species that has plenty of biomass, yet has a fairly low impact on the

community’s organization

(3) A rare species that has minimal impact on the biomass and on other species in the

community

(4) A dominant species that constitutes a large proportion of the biomass and which affects

may other species

47. The inherent maximum capacity of an organism to reproduce or increase in number is called

as [DUMET 2008]

(1) biotic potential (2) ecosystem (3) population (4) ecology

48. Match the column I with column II and choose the correct option [Kerala CEE 2008]

Column I Column II

A. Mutualism 1. Tiger and deer

B. Commensalism 2. Cuscuta on Citrus

C. Parasitism 3. Sucker fish and shark

D. Predation 4. Lichen

(1) A – 1, B – 2, C – 3, D – 4 (2) A – 4, B – 3, C – 2, D – 1

(3) A – 1, B – 3, C – 2, D – 4 (4) A – 2, B – 3, C – 1, D – 4

(e) A – 4, B – 2, C – 3, D – 1

49. If the strong partner is benefited and the weak partner is damaged. It is known as[J&K CET

2008]

(1) Predation (2) allelopathy (3) symbiosis (4) commensalisms



50. In the association between two organisms, if one organism is benefited and the other is not

benefited, this relationship is known as [J&K CET 2008]

(1) symbiosis (2) mutualism (3) commensalism (4) parasitism

51. NEERI is [HMT CET 2007]

(1) National Ethological and Ecological Research Institute

(2) National Eugenics and Ecological Research Institute

(3) National Ecological and Environment Research Institute

(4) National Environmental Engineering Research Institute

52. A0 layer is rich in [UP CPMT 2007]

(1) minerals (2) humus (3) litter (4) None of these

53. Column I represents the size of the soil particles and column II represents type of soil

components. Which of the following is correct match for the column I and column II?

Column I Column II

A. 0.2 to 2.00 mm 1. Silt

B. Less than 0.002 mm 2. Clay

C. 0.02 to 0.2 mm 3. Coarse and particle

D. 0.002 to 0.02 mm 4. Fine sand particle

(1) A – 2, B – 3, C – 4, D – 1 (2) A – 4, B – 1, C – 3, D – 2

(3) A – 3, B – 2, C – 4, D – 1 (4) A – 3, B – 1, C – 2, D – 4

54. Geometric representation of age structure is a characteristic of [CBSE AIPMT 2007]

(1) biotic community (2) population (3) landscape (4) ecosystem

55. The population of an insect species shows an explosive increase in numbers during rainy

season followed by it disappearance at the end of the season. What does this show?

(1) S-shpaed or sigmoid growth of this insect [CBSE AIPMT 2007]

(2) The food plants mature and die at the end of rainy season

(3) Its population growth curve is of J-type

(4) the population of its predators increases enormously

56. Who stated that human population grows geometrically? [AMU 2007]

(1) Malthus (2) Darwin (3) Cannon (4) Lamarck

57. The permanent decrease in population number occurs due to [BHU 2007]

(1) migration (2) natality (3) emigration (4) mortality

58. If non-limiting condition are provided then what will happen? [DUMET 2007]

(1) Natality increases and mortality decreases

(2) Mortality decreases

(3) Natality increases

(4) Mortality increases

59. Competition of species leads to [DUMET 2007]

(1) extinction (2) mutation

(3) greater number of niches are formed (4) symbiosis

60. Population density of terrestrial organisms is measured in terms of individuals per [KCET

2007]

(1) m3 (2) m

4 (3) m (4) m

2



61. When two related populations occupy geographically or spatially separate areas, they are

called [Kerala CEE 2007]

(1) allopatric population (2) quantum population

(3) saltational population (4) parapatric population

62. Which of the following statements regarding species interdependence are true?

I. An association of two species where one is benefited and other remains unaffected is

called mutualism.

II. An interspecific association where both partners derive benefit from each other is called

commensalism

III. A direct food relation between two species of animals in which one animal kills and feeds

on another is referred as predation

IV. A relationship between two species or organisms where both the partners are benefited

from each other is called symbiosis. [Kerala CEE 2007]

(1) I and II only (2) III and IV only (3) I and III only (4) II and III only

(e) II and IV only

63. They are dominant plants of the cold desert [Guj CET 2007]

(1) shrub and small tress (2) low stature shrub and perennial grass

(3) tall trees and herbaceous plants (4) low stature shrub and herbaceous plants

64. Root cap is not found in [BCECE 2007]

(1) mesophytes (2) xerophytes (3) hydrophytes (4) halophytes

65. The percentage of soil volume occupied by pore space is called porosity of soil. It is

minimum in [Manipal 2006]

(1) sandy soil (2) clay soil (3) loamy soil (4) silt

66. Niche overlap indicates [CBSE AIPMT 2006]

(1) active cooperation between two species

(2) two different parasites on the same host

(3) sharing of one or more resources between the two species

(4) mutualism between two species

67. There is more competition for survival between [AFMC 2006]

(1) different animals of same niche (2) same animals of same niche

(3) different animals of different niche (4) same animals of different niche

68. Which one of the following is a matching pair of certain organism(s) and the kind of

association? [AIIMS 2006]

(1) Shark and sucker fish – Commensalism

(2) Red algae and fungi in lichens – Mutualism

(3) Orchids growing on trees – Parasitism

(4) Cuscuta (dodder) growing on other flowering plants – Epiphysis

69. Submerged hydrophytes show [UP CPMT 2006]

(1) stomata (2) abundant air sacs

(3) well developed mechanical tissue (4) secondary growth



70. The desert plants in order to tolerate water stress, show [Punjab PMET 2006]

(1) sunken stomata (2) reduced leaves

(3) well developed root system (4) All of the above

71. Viscum album grows on trees. This is an example of [DUMET 2006]

(1) symbiosis (2) parasitism (3) commensalisms (4) predation

72. Species living in a restricted geographical area is [DUMET 2006]

(1) sympatric (2) allopatric (3) sibling (4) keystone

73. Biotic potential or potential natality means [EAMCET 2006]

(1) natural increase of population under ideal/optimum conditions

(2) potential of organism in a biome (3) number of organisms in a biome

(4) species of maximum number in a population

74. Association of animals belonging to different species, where both partners are benefited, is

called [Manipal 2006]

(1) commensalisms (2) Mutualism (3) colony (4) sympathy

75. Keystone species deserve protection because these [Haryana PMT 2006]

(1) are capable of surviving in harsh environmental condition

(2) indicate presence of certain minerals in the soil

(3) have become rare due to over exploitation

(4) play an important role in supporting other species

76. The relationship between the alga Microcystis and the surroundings fauna correspond to

(1) amensalism (2) parasitism [BCECE 2006]

(3) predation (4) exploitation

77. Study of environment and animal relation is [RPMT 2005]

(1) Ecosystem (2) Phytosociology (3) Biotic community (4) Ecology

78. Humus is present in [UP CPMT 2005]

(1) horizon-A (2) horizon-O (3) horizon – B (4) horizon-C

79. Living in same habitat, organisms of same species form [UP CPMT 2005]

(1) biosphere (2) community (3) population (4) niche

80. The organisms inhabiting a common environment belong to the same [AMU 2005]

(1) species (2) genus (3) population (4) community

81. Ephemerals are xerophytes that are [BHU 2005]

(1) drought resisting (2) drought enduring (3) drought escaping (4) None of these

82. Plants which behave as mesophytes in rainy season and as xerophytes in summers are called

(1) xerophytes (2) mesophytes [Punjab PMET 2005]

(3) trophophytes (4) phreatophytes

83. In India, human population heavily weighted towards the younger age group as a result of

(1) short life span of many individuals and low birth rate [DUMET 2005]

(2) short life span of many individuals and high birth rate

(3) long life span of many individuals and high birth rate

(4) long life span of many individuals and low birth rate



84. Different types of interactions and the nature of interactions between species ‘A’ and ‘B’ are

given in column I and II respectively. Choose the correct answer key where they are matched.

Column I Column II

A. Mutualism 1. Beneficial to ‘A’ and no effect on ‘B’

B. Competition 2. Beneficial to both ‘A’ and ‘B’

C. Parasitism 3. Beneficial to ‘A’ and inhibitory for ‘B’

D. Predation 4. Beneficial to ‘A’ and harmful to ‘B’

E. Commensalisms 5. Harmful both ‘A’ and ‘B’

(1) A – 5, B – 4, C – 1, D – 2, E – 3 (2) A – 1, B – 3, C – 2, D – 5, E – 4

(3) A – 2, B – 5, C – 4, D – 3, E – 1 (4) A – 3, B – 1, C – 2, D – 4, E – 5

85. The type of population, where pre-reproductive animals occur in large number, is

(1) declining (2) fluctuating (3) stable (4) growing [EAMCET

2005]

86. If natality rate is parallel to mortality rate then population [MHT CET 2005]

(1) slowly increases (2) remains stationary

(3) shows J-shaped curve (4) slowly decreases

87. Plants growing in dry and saline soil are called

(1) xerophyte (2) hydrophyte [RPMT 2005]

(3) halophyte (4) heliophyte

88. Sea plants are an example of [BCECE 2005]

(1) xerophyte (2) mesophyte (3) hydrophyte (4) submerged plant

89. Term ‘ecology’ was given by [AFMC 2004]

(1) Reiter (2) Cuvier (3) Haeckel (4) Malthus

90. The study of population is called

(1) Demography`(2)`Population explosion (3)`Polpulation dynamics (4) Census

91. Good soil is that which [UP CPMT 2004]

(1) holds whole of the water that enters into it

(2) allows percolating the water slowly from it

(3) allows water to pass very quickly from it

(4) allows limited amount of water to retain into it

92. In which one of the following habitats does the diurnal temperature of soil surface vary most?

(1) Shrub land (2) Forest [CBSE AIPMT 2004]

(1) Desert (4) Grassland

93. Which of the following is not true for a species? [CBSE AIPMT 2004]

(1) Members of a species can interbreed

(2) Variations occur among members of a species

(3) Each species is reproductively isolated from every other species

(4) Gene flow does not occur between the populations of a species

94. The maximum growth rate occurs in [CBSE AIPMT 2004]

(1) stationary phase (2) senescent phase (3) lag phase (4) exponential phase



95. Which of the following supports a dense population of plankton and littoral vegetation?

[BHU 2004]

(1) Oligotrophic (2) Eutrophic (3) Lithotrophic (4) Agroecotrophic

96. In a population, the condition at which the rate of addition of new members is more than the

rate of individuals lost indicates [Kerala CEE 2004]

(1) zero population growth (2) exponential growth

(3) fluctuating growth (4) declining growth

97. Population growth curve in most animals, except human is [HMT CET 2004]

(1) S-shaped (2) J-shaped

(3) J-shaped with tail (4) S-shaped with tail

98. Plants developing in dry conditions are [BCECE 2004]

(1) xerophytes (2) mesophytes (3) lithophytes (4) hydrophytes

99. A sedentary sea anemone gets attached to the shell lining of hermit crab. The association is

(1) Amensalism (2) Ectoparasitism [NEET 2013]

(3) Symbiosis (4) Commensalism

100. A biologist studied the population of rats in a barn. He found that the average natality was

250, average mortality 240, immigration 20 and emigration 30. The net increase in population

is : [NEET 2013]

(1) zero (2) 10 (3) 15 (4) 05

101. Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot

summer, thousands of migratory birds from Siberia and other extremely cold northern regions

move to: [CBSE AIPMT 2014]

(1) Corbett National Park (2) Keolado national Park

(3) Western Ghat (4) Meghalaya

102. The following graph depicts changes in two populations (A and B) of herbivores in a grassy

field. A possible reason for these changes is that: [CBSE AIPMT 2015]

(1) Population B competed more successfully for food than population A

(2) Population A produced more offspring than population B

(3) Population A consumed the members of population B

(4) Both plant populations in this habitat decreased

103. Gause’s principle of competitive exclusion states that [CBSE AIPMT 2016]

(1) Competition for the same resources excludes species having different food preference

(2) No two species can occupy the same niche indefinitely for the same limiting resources

(3) Larger organisms exclude smaller ones through competition

(4) More abundant species will exclude the less abundant species through competition



104. It is much easier for a small animal to run uphill than for a large animal, because; [CBSE

AIPMT 2016] (1) Smaller animals have a higher metabolic rate

(2) Small animals have a lower O2 requirement

(3) The efficiency of muscles in large animals is less than in the small animals.

(4) It is easier to carry a small body weight.

105. When does the growth rate of a population following the logistic model equal zero? The

logistic model is given as dN / dt = rN(1-N/K) : [NEET -I 2016]

(1) when N nears the carrying capacity of the habitat.

(2) when N/K equals zero.

(3) when death rate is greater than birth rate.

(4) when N/K is exactly one.

106. The primary producers of the deep-hydrothermal vent ecosystem are [NEET-II 2016]

(1) green algae (2) chemosynthetic bacteria

(3) blue-green algae (4) coral reefs

107. Which of the following is correct for-selected species? [NEET-II 2016]

(1) Large number of progeny with small size (2) Large number of progeny with large

size

(3) Small number of progeny with small size (4) Small number of progeny with large

size

108. If ‘+’ sign is assigned to beneficial interaction, ‘–’ sign to detrimental and ‘0’ sign to neutral

interaction, then the population interaction represented by ‘+’ ‘–’ refers to [NEET-II 2016]

(1) mutualism (2) amensalism (3) commensalism (4) parasitism

109. The principle of competitive exclusion was stated by [NEET-II 2016]

(1) C. Darwin (2) G. F. Gause

(3) MacArthur (4) Verhulst and Pearl



EXERCISE (KEY) LEVEL–I(CLASS WORK)

1. (1)

2. (2)

3. (1)

4. (1)

5. (1)

6. (2)

7. (4)

8. (1)

9. (2)

10. (3)

11. (2)

12. (1)

13. (3)

14. (2)

15. (2)

16. (1)

17. (4)

18. (2)

19. (1)

20. (3)

21. (2)

22. (1)

23. (3)

24. (2)

25. (1)

26. (4)

27. (2)

28. (1)

29. (3)

30. (3)

LEVEL–II(HOME WORK)

1. (3)

2. (3)

3. (2)

4. (3)

5. (4)

6. (4)

7. (2)

8. (3)

9. (2)

10. (3)

11. (3)

12. (1)

13. (1)

14. (1)

15. (2)

16. (2)

17. (4)

18. (1)

19. (2)

20. (2)

21. (1)

22. (1)

23. (2)

24. (4)

25. (4)

26. (1)

27. (3)

28. (4)

29. (2)

30. (3)

31. (1)

32. (3)

33. (1)

ASSERTION & REASON QUESTIONS (CLASS WORK)

1. (1)

2. (2)

3. (2)

4. (3)

5. (1)

6. (1)

7. (2)

8. (2)

9. (1)

10. (1)

11. (2)

12. (1)

13. (1)

14. (2)

15. (1)

16. (1)

17. (1)

PREVIOUS YEAR QUESTIONS (HOME WORK)

1. (3)

2. (3)

3. (1)

4. (1)

5. (2)

6. (3)

7. (3)

8. (1)

9. (3)

10. (4)

11. (3)

12. (2)

13. (1)

14. (1)

15. (3)

16. (2)

17. (1)

18. (2)

19. (1)

20. (3)

21. (4)

22. (3)

23. (2)

24. (2)

25. (4)

26. (3)

27. (4)

28. (1)

29. (3)

30. (3)

31. (2)

32. (2)

33. (2)

34. (2)

35. (3)

36. (4)

37. (2)

38. (2)

39. (1)

40. (1)

41. (2)

42. (3)

43. (1)

44. (3)

45. (2)

46. (1)

47. (1)

48. (2)

49. (1)

50. (3)

51. (4)

52. (2)

53. (3)

54. (2)

55. (3)

56. (1)

57. (4)

58. (1)

59. (1)

60. (4)

61. (1)

62. (2)

63. (4)

64. (3)

65. (2)

66. (2)

67. (2)

68. (1)

69. (2)

70. (4)

71. (2)

72. (1)

73. (1)

74. (2)

75. (4)

76. (1)

77. (4)

78. (1)

79. (3)

80. (4)

81. (3)

82. (3)

83. (2)

84. (3)

85. (4)

86. (2)

87. (3)

88. (3)

89. (1)

90. (1)

91. (2)

92. (3)

93. (4)

94. (4)

95. (2)

96. (2)

97. (1)

98. (1)

99. (4)

100. (1)

101. (2)

102. (1)

103. (2)

104. (1)

105. (4)

106. (2)

107. (1)

108. (4)

109. (2)

INDEX

Topic Name Page No


Exercise 115- 136

Level–I 115-119

Level–II 119-122



Answer Key 137-137

This Chapter Includes: Introduction

Ecosystem – Structure and Function

Pond Ecosystem

Productivity

Decomposition

Energy Flow

Pyramids of Numbers

Pyramids of Biomass

Pyramids of Energy

Ecological Efficiencies

Ecological Succession

Process of Succession

Succession of Plants

Nutrient cycling

Ecosystem – Carbon Cycle

Ecosystem Services

ECOSYSTEM

Ecosystem Rg.-Bot. XII-19-21


INTRODUCTION

The term ecosystem was coined by Sir Arthur Tansley in 1935.

An ecosystem can be visualised as a functional unit of nature, where living organisms interact

among themselves and also with the surrounding physical environment.

Ecosystem varies greatly in size from a small pond to a large forest or a sea. Many ecologists

regard the entire biosphere as a global ecosystem, as a composite of all local ecosystems on

Earth.

Since this system is too much big and complex to be studied at one time, it is convenient to divide it

into two basic categories, namely the terrestrial and the aquatic. Forest, grassland and

desert are some examples of terrestrial ecosystems; pond, lake, wetland, river and estuary are

some examples of aquatic ecosystems. Crop fields and an aquarium may also be considered

as man-made ecosystems.

First look at the structure of the ecosystem, in order to appreciate the input (productivity),

transfer of energy (food chain/web, nutrient cycling) and the output (degradation and energy

loss), then look at the relationships – cycles, chains, webs – that are created as a result of these

energy flows within the system and their inter- relationship.

An ecosystem has two basic components: (i) abiotic (non-living) and (ii) biotic (living

organisms).

Abiotic components comprise inorganic materials (e.g., carbon, nitrogen, oxygen, CO2,

water, etc.) and dead organic matter containing proteins, carbohydrates, lipids, humic

substance, etc. Abiotic substances are present in soil, water and air. The climatic parameters

like solar radiation and temperature determine the abiotic conditions within which the

organisms carry out life functions

Biotic components include producers, consumers and decomposers. Producers are the

autotrophs, which produce their own food. A variety of photosynthetic bacteria, chemosynthetic

bacteria and photosynthetic protozoa also produce organic substances in terrestrial and

aquatic habitats, though in very small amounts. In terrestrial ecosystems, the autotrophs are

usually rooted plants (herbs, shrubs and trees), whereas in deep aquatic ecosystems, floating

plants called phytoplankton are the major autotrophs. In shallow waters rooted plants,

macrophytes, are the dominant producers. When the environmental conditions are optimum,

the phytoplankton may produce as much food as produced by the larger shrubs and trees on

unit area (land or water surface) basis.

Consumers or phagotrophs or heterotrophs: A consumer, which derives nutrition by eating

plants, is called primary consumer or herbivore. The secondary consumer or carnivore is an

animal that depends upon the flesh of herbivore or other animals.

Decomposers or saprotrophs consisting mostly of bacteria and fungi, which live on dead

organic matter or detritus, the decomposers do not ingest their food. Instead, they release

different enzymes from their bodies into the dead and decaying plant and animal remains. The

extra cellular digestion of the dead remains, leads to the release of simpler inorganic

substances, which are then, utilized by the decomposers. The producers from the first trophic

ECOSYSTEM



level, herbivores the second, and carnivores constitute and third.

ECOSYSTEM – STRUCTURE AND FUNCTION

In earlier topic we studied various components of the environment- abiotic and biotic, and also

studied how the individual biotic and abiotic factors affected each other and their surrounding.

Now look at these components in a more integrated manner and see how the flow of energy takes

place within these components of the ecosystem.

Interactions of biotic and abiotic components result in a physical structure that is characteristic

for each type of ecosystem. Identification and enumeration of plant and animal species of an

ecosystem gives its species composition. Vertical distribution of different species occupying

different levels is called stratification. For example, trees occupy top vertical strata or layer of a

forest, shrubs the second and herbs and grasses occupy the bottom layers.

The components of the ecosystem are seen to function as a unit when we consider the following

aspects:

i) Productivity; ii) Decomposition; iii) Energy flow; and iv) Nutrient cycling.

POND ECOSYSTEM

To understand an aquatic ecosystem let us take a small pond as an example. This is fairly a self-

sustainable unit and rather simple example that explain even the complex interactions that exist in an

aquatic ecosystem.

A pond is a shallow water body in which all the above mentioned four basic components of an

ecosystem are well exhibited.

The abiotic component is the water with all the dissolved inorganic and organic substances and

the rich soil deposit at the bottom of the pond. The solar input, the cycle of temperature, day-

length and other climatic conditions regulate the rate of function of the entire pond.

The autotrophic components include the phytoplankton, some algae and the floating,

submerged and marginal plants found at the edges.

The consumers are represented by the zooplankton, the free swimming and bottom dwelling

forms.

The decomposers are the fungi, bacteria and flagellates especially abundant in the bottom of the

pond.

This system performs all the functions of any ecosystem and of the biosphere as a whole, i.e.,

conversion of inorganic into organic material with the help of the radiant energy of the sun by the

autotrophs; consumption of the autotrophs by heterotrophs; decomposition and mineralisation of

the dead matter to release them back for reuse by the autotrophs, these event are repeated over and

over again.

There is unidirectional movement of energy towards the higher trophic levels and its

dissipation and loss as heat to the environment.

PRODUCTIVITY

A constant input of solar energy is the basic requirement for any ecosystem to function and sustain.

Primary production is defined as the amount of biomass or organic matter produced per unit

area over a time period by plants during photosynthesis. It is expressed in terms of weight (g –2)

or energy (kcal m–2).

The rate of biomass production is called productivity. It is expressed in terms of g –2 yr –1

or (kcal m–2) yr –1 to compare the productivity of different ecosystems. It can be divided into

gross primary productivity (GPP) and net primary productivity (NPP).

Gross primary productivity of an ecosystem is the rate of production of organic matter during



photosynthesis. A considerable amount of GPP is utilised by plants in respiration. Gross primary

productivity minus respiration losses (R), is the net primary productivity (NPP).

GPP – R = NPP

Net primary productivity is the available biomass for the consumption to heterotrophs (herbiviores

and decomposers). Secondary productivity is defined as the rate of formation of new

organic matter by consumers.

Primary productivity depends on the plant species inhabiting a particular area. It also depends on a variety of environmental factors, availability of nutrients and photosynthetic capacity of plants. Therefore, it varies in different types of ecosystems. The annual net primary productivity of the whole biosphere is approximately 170 billion tons (dry weight) of organic matter. Of this, despite occupying about 70 per cent of the surface, the productivity of the oceans are only 55 billion tons. Rest of course, is on land.

DECOMPOSITION

Earthworm is often referred to as the farmer‘s ‗friend‘, this is so because they help in the

breakdown of complex organic matter as well as in loosening of the soil. Similarly, decomposers

break down complex organic matter into inorganic substances like carbon dioxide, water and

nutrients and the process is called decomposition.

Dead plant remains such as leaves, bark, flowers and dead remains of animals, including fecal

matter, constitute detritus, which is the raw material for decomposition. The important steps

in the process of decomposition are fragmentation, leaching, catabolism, humification and

mineralisation.

Detritivores (e.g., earthworm) break down detritus into smaller particles. This process is called

fragmentation.

By the process of leaching, water- soluble inorganic nutrients go down into the soil horizon and get

precipitated as unavailable salts.

Bacterial and fungal enzymes degrade detritus into simpler inorganic substances. This process is

called as catabolism

Diagrammatic representation of decomposition cycle in a terrestrial ecosystem



It is important to note that all the above steps in decomposition operate simultaneously on the detritus.

Humification and to accumulation of a dark coloured amorphous substance called humus that

is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.

Being colloidal in nature it serves as a reservoir of nutrients.

The humus is further degraded by some microbes and release of inorganic nutrients occur by the

process known as mineralisation.

Decomposition is largely an oxygen-requiring process. The rate of decomposition is

controlled by chemical composition of detritus and climatic factors.

In a particular climatic condition, decomposition rate is slower if detritus is rich in lignin and

chitin, and quicker, if detritus is rich in nitrogen and water-soluble substances like sugars.

Temperature and soil moisture are the most important climatic factors that regulate

decomposition through their effects on the activities of soil microbes. Warm and moist

environment favour decomposition whereas low temperature and anaerobiosis inhibit

decomposition resulting in build up of organic materials.

ENERGY FLOW

Except for the deep sea hydro-thermal ecosystem, sun is the only source of energy for all

ecosystems on Earth. Of the incident solar radiation less than 50 per cent of it is

photosynthetically active radiation (PAR).

Plants and photosynthetic and chemosynthetic bacteria (autotrophs), fix sun‘s radiant energy to

make food from simple inorganic materials. Plants capture only 2-10 per cent of the PAR and

this small amount of energy sustains the entire living world. So, it is very important to know how the

solar energy captured by plants flows through different organisms of an ecosystem. All

organisms are dependent for their food on producers, either directly or indirectly. So unidirectional

flow of energy from the sun to producers and then to consumers takes place. (First law of

thermodynamics)

Further, ecosystems are not exempt from the Second Law of thermodynamics. They

need a constant supply of energy to synthesise the molecules they require, to counteract the

universal tendency toward increasing disorderliness.



The green plant in the ecosystem-terminology are called producers.In a terrestrial ecosystem,

major producers are herbaceous and woody plants. Likewise, primary producers in an aquatic

ecosystem are various species like phytoplankton, algae and higher plants.

Starting from the plants (or producers) food chains or rather webs are formed such that an

animal feeds on a plant or on another animal and in turn is food for another. The chain or web is

formed because of this interdependency. No energy that is trapped into an organism remains in it

for ever. The energy trapped by the producer, hence, is either passed on to a consumer or the

organism dies. Death of organism is the beginning of the detritus food chain/web.

All animals depend on plants (directly or indirectly) for their food needs.

They are hence called consumers and also heterotrophs. If they feed on the producers, the

plants, they are called primary consumers, and if the animals eat other animals which in turn eat

the plants (or their produce) they are called secondary consumers. Likewise, tertiary consumers

too.

Obviously the primary consumers will be herbivores. Some common herbivores are insects,

birds and mammals in terrestrial ecosystem and molluscs in aquatic ecosystem.

The consumers that feed on these herbivores are carnivores, or more correctly primary

carnivores (though secondary consumers). Those animals that depend on the primary

carnivores for food are labelled secondary carnivores. A simple grazing food chain (GFC) is

depicted below:

The detritus food chain (DFC) begins with dead organic matter. It is made up of decomposers

which are heterotrophic organisms, mainly fungi and bacteria. They meet their energy and

nutrient requirements by degrading dead organic matter or detritus. These are also known as

saprotrophs (sapro: to decompose). Decomposers secrete digestive enzymes that

breakdown dead and waste materials into simple, inorganic materials, which are subsequently

absorbed by them.

In an aquatic ecosystem, GFC is the major conduit for energy flow. As against this, in a terrestrial

ecosystem, a much larger fraction of energy flows through the detritus food chain than through

the GFC. Detritus food chain may be connected with the grazing food chain at some levels: some

of the organisms of DFC are prey to the GFC animals, and in a natural ecosystem, some animals like

cockroaches, crows, etc., are omnivores. These natural interconnection of food chains make it a

food web.

Organisms occupy a place in the natural surroundings or in a community according to their

feeding relationship with other organisms. Based on the source of their nutrition or food, organisms

occupy a specific place in the food chain that is known as their trophic level. Producers belong

to the first trophic level, herbivores (primary consumer) to the second and carnivores

(secondary consumer) to the third.



Diagrammatic representation of trophic levels in an ecosystem

The important point to note is that the amount of energy decreases at successive trophic levels.

When any organism dies it is converted to detritus or dead biomass that serves as an energy

source for decomposers.

Organisms at each trophic level depend on those at the lower trophic level for their energy

demands. Each trophic level has a certain mass of living material at a particular time called as the

standing crop. The standing crop is measured as the mass of living organisms (biomass) or

the number in a unit area. The biomass of a species is expressed in terms of fresh or dry

weight. Measurement of biomass in terms of dry weight is more accurate.

The number of trophic levels in the grazing food chain is restricted as the transfer of energy

follows 10 per cent law – only 10 per cent of the energy is transferred to each trophic level from

the lower trophic level. In nature, it is possible to have so many levels – producer, herbivore, primary

carnivore, secondary carnivore in the grazing food chain.

The productivity of each trophic level is much less than the productivity of the trophic level it

feeds on. This is because some energy is lost as heat, some production is never eaten but

goes into the detritus pool, and some of what is eaten passes through the gut and into the

detritus pool as faeces. The percentage of the productivity of the trophic level, which enters the

next trophic level, is called transfer efficiency. Transfer efficiencies are only about 10% i.e., the

rate at which energy passes into each trophic level is about 10% of that entering the previous

level. This is called the 10% law. (An American ecologist, Raymond L. Lindeman).

Thus a sharp decline in productivity from one trophic level to the next sets the limit to the

number of trophic levels. The maximum number of links found in food chains appears to be

about seven, but food chains with between three to five links is common.



Energy flow through different trophic levels

A food chain – 1. Producer – Grass 2. Primary consumer-Grasshopper 3. Secondary consumer-Frog

4. Tertiary consumer-Snake 5. Quaternary top consumer-Eagle.

ECOLOGICAL PYRAMIDS

A pyramidal structure is obtained when food or energy relationship between organisms at

different trophic level is expressed. Thus, relationship is expressed in terms of number,

biomass or energy. The base of each pyramid represents the producers or the first trophic level

while the apex represents tertiary or top level consumer. The three ecological pyramids that are

usually studied are (1) pyramid of number; (2) pyramid of biomass and (3) pyramid of energy.

PYRAMIDS OF NUMBERS These show the numbers of individuals at each trophic level. The length of each bar is

proportional to the number of organisms. It was the British ecologist Charles Elton who is 1927, first recognized that such a diagrams often forms a pyramid. Pyramids of numbers are therefore sometimes referred to as Eltonian pyramids. In number pyramids there are fewer individuals in each higher trophic levels are (i) predators are generally larger than their prey, and (ii) at higher trophic levels, less energy enters, and so is distributed to fewer individuals.

However pyramid of numbers need not always be pyramid shaped. They could be bulged at the middle, when the producers are larger and few in number as in forest ecosystem or inverted when the consumer carry parasites.



PYRAMIDS OF BIOMASS These show the dry weight of the organisms (the standing crop) in the trophic levels at a

particular point of time. The length of the bars is proportional to the biomass in each level. Biomass represents the chemical energy stored in the organic matter of a trophic level. Biomass pyramids generally narrow sharply from producers at the bases to top-level carnivores at the apex because energy transfers between trophic levels are so inefficient. Some aquatic ecosystems, however, have inverted biomass pyramids, with primary consumers outweighing producers. For example, the biomass of diatoms in a lake is very small, because the zooplankton consumes them so quickly that the producers never develop a large population size or standing crop. Instead, the phytoplankton (diatoms) has a high turnover rate. They grow, reproduce and are consumed rapidly. Nevertheless, productivity by the phytoplankton is fairly high, and the energy pyramid for this ecosystem is upright.

Pyramids of Biomass (1) a field and (2) a lake

PYRAMIDS OF ENERGY

These are the most useful type of pyramids. The length of the bar represents the productivity of one trophic level in an ecosystem. These show how much energy passes from one trophic level to the next. Because only a proportion of energy in a level is transferred to the next, energy pyramids are never inverted nor do they have a central bulge.

(1) Pyramid of numbers in a grassland ecosystem. Only three top-carnivores are supported in an ecosystem based on production of nearly 6 millions plants

Numbers of 2° consumers1° consumers

producers

Foxes

Rabbits

Grass

Pyramids of numbers

Blue tits


producers

Caterpillars

tree

Aphids


producers

Parasites

Rose bush

Pyramids of biomass (a) a field and

(b) a lake

1° consumersproducers

ZooplanktonPhytoplankton

Standing crop2° consumers1° consumersproducers

2)(gm1.0

6.0

0.470

0.21

0.4

)(a )(b

Pyramid of energy

Energy transferred

2° consumers1° consumersproducers

)ym10(kJ 123 09.0

60.1

10.14



(2) Pyramid of biomass shows a sharp decrease in biomass at higher trophic levels

(3) Inverted pyramid of biomass-small standing crop of phytoplankton supports large

standing crop of zooplankton

(4) An ideal pyramid of energy. Observe that primary producers convert only 1% of the

energy in the sunlight available to them into NPP

Any calculations of energy content, biomass, or numbers has to include all organisms at that

trophic level. No generalisations will be true if only a few individuals at any trophic level is

taken into account.

Also a given organism may occupy more than one trophic level simultaneously. One must

remember that the trophic level represents a functional level, not a species as such. A given

species may occupy more than one trophic level in the same ecosystem at the same time; for

example, a sparrow is a primary consumer when it eats seeds, fruits, peas, and a secondary

consumer when it eats insects and worms.

In most ecosystems, all the pyramids, of number, of energy and biomass are upright, i.e.,

producers are more in number and biomass than the herbivores, and herbivores are more in

number and biomass than the carnivores. Also energy at a lower trophic level is always more

than at a higher level.

There are exceptions to this generalisation: count the number of insects feeding on a big tree.

Now add an estimate of the number of small birds depending on the insects, as also the number

of larger birds eating the smaller.

The pyramid of biomass in sea is also generally inverted because the biomass of fishes far

exceeds that of phytoplankton.

Pyramid of energy is always upright, can never be inverted, because when energy flows from a

particular trophic level to the next trophic level, some energy is always lost as heat at each step.

Each bar in the energy pyramid indicates the amount of energy present at each trophic level in a



given time or annually per unit area.

However, there are certain limitations of ecological pyramids such as it does not take into account

the same species belonging to two or more trophic levels. It assumes a simple food chain,

something that almost never exists in nature; it does not accommodate a food web. Moreover,

saprophytes are not given any place in ecological pyramids even though they play a vital role in

the ecosystem.

ECOLOGICAL EFFICIENCIES

Ratios between energy flow at different points along the food chain when expressed as

percentages are called ecological efficiencies. Efficiency ratios are meaningful in comparisons

only when they are dimensionless, that is when numerator and denominator of each ratio are

expressed in the same unit.

The photosynthetic efficiency measures the ability to utilize incident solar radiation expressed

in relation to PAR (Photosynthetically Active Radiation) or visible light. Net production

efficiency varies from one species to other depending on growth forms; whereas algae have

high net production efficiency, trees have a lower value since they have huge non-

photosynthetic biomass.

At the consumer level one can talk about assimilation efficiency with reference to that particular

trophic level and ecological efficiency or trophic levels. The various efficiencies can be

calculated using different formulae as given below;

Photosynthetic efficiency radiationsolartotalIncident

100typroductiviprimaryGross

Net production efficiency typroductiviprimaryGross

100typroductiviprimaryNet

Assimilation efficiency ingestedenergyFood

100dassimilateenergyFood

Ecological efficiency leveltrophicpreviousatproductionbiomassinEnergy

100leveltrophicaatproductionbiomassinEnergy

ECOLOGICAL SUCCESSION

The characteristics of population and community and also their response to environment and

how such responses vary from an individual response. Let us examine another aspect of community

response to environment over time.

An important characteristic of all communities is that composition and structure constantly

change in response to the changing environmental conditions. This change is orderly and

sequential, parallel with the changes in the physical environment. These changes lead finally to a

community that is in near equilibrium with the environment and that is called a climax

community. The gradual and fairly predictable change in the species composition of a given

area is called ecological succession. During succession some species colonise an area and

their populations become more numerous, whereas populations of other species decline and even

disappear.

The entire sequence of communities that successively change in a given area are called

sere(s). The individual transitional communities are termed seral stages or seral communities. In

the successive seral stages there is a change in the diversity of species of organisms, increase in

the number of species and organisms as well as an increase in the total biomass.

The present day communities in the world have come to be because of succession that has



occurred over millions of years since life started on earth. Actually succession and evolution

would have been parallel processes at that time.

Succession is hence a process that starts where no living organisms are there – these could be

areas where no living organisms ever existed, say bare rock; or in areas that somehow, lost all the

living organisms that existed there. The former is called primary succession, while the latter is

termed secondary succession.

Examples of areas where primary succession occurs are newly cooled lava, bare rock, newly

created pond or reservoir. The establishment of a new biotic community is generally slow.

Before a biotic community of diverse organisms can become established, there must be soil.

Depending mostly on the climate, it takes natural processes several hundred to several thousand

years to produce fertile soil on bare rock.

Secondary succession begins in areas where natural biotic communities have been

destroyed such as in abandoned farm lands, burned or cut forests, lands that have been

flooded. Since some soil or sediment is present, succession is faster than primary succession.

Description of ecological succession usually focuses on changes in vegetation. However, these

vegetational changes in turn affect food and shelter for various types of animals. Thus, as

succession proceeds, the numbers and types of animals and decomposers also change.

At any time during primary or secondary succession, natural or human induced

disturbances (fire, deforestation, etc.), can convert a particular seral stage of succession to an

earlier stage. Also such disturbances create new conditions that encourage some species

and discourage or eliminate other species.

PROCESS OF SUCCESSION

Major steps in a primary autotrophic succession are as follows:

1. Nudation: Exposure of an area

2. Migration: The process of dispersal of seeds, spores and other structure of propagation of the

species to bare area is known as migration.

3. Germination: It occurs when conditions are favourable.

4. Ecesis: Successful germination of propagules and its establishment in a bare area is known as

ecesis.

5. Colonisation and Aggregation: After ecesis, the individuals of the species increase in number as

the result of reproduction.

6. Competition and Co-action: Due to limited resources, species show both inter and intraspecific

competition. This results into elimination of unsuitable and weaker plants.

7. Invasion: Various other types of plants try to establish in the spaces left by the elimination of

previous plants due to competition.

8. Reaction: The newly arrived plants interrupt with the existing ones. As the result of reaction,

environment is modified and becomes unsuitable for the existing community which sooner or

later is replaced by another community.

9. Stabilization: The process when the final climax community becomes more or less stabilized for

a longer period of time and it can maintain itself in equilibrium with the climate of the area. As

compared to transitional communities, the climax community has larger size of individuals,

complex organization, complex food chains and food webs, more efficient energy use and more

nutrient conservation.

SUCCESSION OF PLANTS



Based on the nature of the habitat – whether it is water (or very wet areas) or it is on very dry areas –

succession of plants is called hydrach or xerarch, respectively.

Hydrarch succession takes place in wetter areas and the successional series progress from

hydric to the mesic conditions. As against this, xerarch succession takes place in dry areas and the

series progress from xeric to mesic conditions. Hence, both hydrarch and xerach successions

lead to medium water conditions (mesic) – neither too dry (xeric) nor too wet (hydric).

The species that invade a bare area are called pioneer species. In primary succession on

rocks these are usually lichens which are able to secrete acids to dissolve rock, helping in

weathering and soil formation. These later pave way to some very small plants like bryophytes,

which are able to take hold in the small amount of soil. They are, with time, succeeded by

bigger plants, and after several more stages, ultimately a stable climax forest community is

formed.

The climax community remains stable as long as the environment remains unchanged. With

time the xerophytic habitat gets converted into a mesophytic one.

In primary succession in water, the pioneers are the small phytoplanktons, they are

replaced with time by free-floating angiosperms, then by rooted hydrophytes, sedges, grasses

and finally the trees. The climax again would be a forest. With time the water body is

converted into land.

In secondary succession the species that invade depend on the condition of the soil,

availability of water, the environment as also the seeds or other propagules present. Since soil is

already there, the rate of succession is much faster and hence, climax is also reached more quickly.

What is important to understand is that succession, particularly primary succession, is a very

slow process, taking maybe thousands of years for the climax to be reached. Another important

fact is to understand that all succession whether taking place in water or on land, proceeds to a

similar climax community – the mesic.



Diagramatic representation of primary succession

NUTRIENT CYCLING

Organisms need a constant supply of nutrients to grow, reproduce and regulate various body

functions. The amount of nutrients, such as carbon, nitrogen, phosphorus, calcium, etc., present in

the soil at any given time, is referred to as the standing state. It varies in different kinds of

ecosystems and also on a seasonal basis.

It is important to appreciate that nutrients are never lost from the ecosystems, they are recycled

time and again indefinitely. The movement of nutrient elements through the various

components of an ecosystem is called nutrient cycling. Another name of nutrient cycling is

biogeochemical cycles (bio: living organism, geo: rocks, air, water).

Simplified model of carbon cycle in the biosphere

Nutrient cycles are of two types: (1) gaseous and (2) sedimentary. The reservoir for gaseous

type of nutrient cycle (e.g., nitrogen, carbon cycle) exists in the atmosphere and for the

sedimentary cycle (e.g., sulphur and phosphorus cycle), the reservoir is located in Earth‘s crust.

Environmental factors, e.g., soil, moisture, pH, temperature etc., regulate the rate of release of



nutrients into the atmosphere. The function of the reservoir is to meet with the deficit which occurs

due to imbalance in the rate of influx and efflux.

You have made a detailed study of nitrogen cycle in class XI. Here we discuss carbon and

phosphorus cycles.

ECOSYSTEM – CARBON CYCLE

In living organisms, carbon constitutes 49 per cent of dry weight of organisms and is next only

to water. Out of the total quantity of global carbon, 71 per cent carbon is found dissolved in oceans.

This oceanic reservoir regulates the amount of carbon dioxide in the atmosphere.

Fossil fuel also represent a reservoir of carbon. Carbon cycling occurs through atmosphere,

ocean and through living and dead organisms. According to one estimate 4 × 1013 kg of

carbon is fixed in the biosphere through photosynthesis annually. A considerable amount

of carbon returns to the atmosphere as CO2 through respiratory activities of the producers

and consumers.

Decomposers also contribute substantially to CO2 pool by their processing of waste materials and

dead organic matter of land or oceans. Some amount of the fixed carbon is lost to sediments and

removed from circulation.

Burning of wood, forest fire and combustion of organic matter, fossil fuel, volcanic activity are additional sources for releasing CO2 in the atmosphere.

Human activities have significantly influenced the carbon cycle. Rapid deforestation and massive

burning of fossil fuel for energy and transport have significantly increased the rate of release of

carbon dioxide into the atmosphere.

Ecosystem – Phosphorus Cycle

Phosphorus is a major constituent of biological membranes, nucleic acids and cellular energy

transfer systems. Many animals also need large quantities of this element to make shells,

bones and teeth.

The natural reservoir of phosphorus is rock, which contains phosphorus in the form of

phosphates. When rocks are weathered, minute amounts of these phosphates dissolve in soil

solution and are absorbed by the roots of the plants.

Herbivores and other animals obtain this element from plants. The waste products and the dead

organisms are decomposed by phosphate-solublising bacteria releasing phosphorus. Unlike

carbon cycle, there is no respiratory release of phosphorus into atmosphere.

A simplified model of phosphorus cycling in a terrestrial ecosystem



The other two major and important differences between carbon and phosphorus cycle are firstly, atmospheric inputs of phosphorus through rainfall are much smaller than carbon inputs, and, secondly, gaseous exchanges of phosphorus between organism and environment are negligible.

ECOSYSTEM SERVICES

Healthy ecosystems are the base for a wide range of economic, environmental and

aesthetic goods and services. The products of ecosystem processes are named as

ecosystem services, for example, healthy forest ecosystems purify air and water, mitigate

droughts and floods, cycle nutrients, generate fertile soils, provide wildlife habitat, maintain

biodiversity, pollinate crops, provide storage site for carbon and also provide aesthetic,

cultural and spiritual values. Though value of such services of biodiversity is difficult to

determine, it seems reasonable to think that biodiversity should carry a hefty price tag.

Robert Constanza and his colleagues have very recently tried to put price tags on nature‘s

life-support services. Researchers have put an average price tag of US $ 33 trillion a year on

these fundamental ecosystems services, which are largely taken for granted because they

are free. This is nearly twice the value of the global gross national product GNP which is

(US $ 18 trillion).

Out of the total cost of various ecosystem services, the soil formation accounts for about 50

per cent, and contributions of other services like recreation and nutrient cycling, are less than

10 per cent each. The cost of climate regulation and habitat for wildlife are about 6 per cent

each.

————




1. Cycling of elements in an ecosystem is called: (1) Chemical cycle (2) Geological cycle (3) Geochemical cycle (4) Biogeochemical cycle

2. The relationship in an ecosystem can be depicted in: (1) Pyramid of energy (2) Pyramid of biomass (3) Pyramid of numbers (4) All of these

3. Which of the following food chains is correct?

(1) Grasses Fox Rabbit

(2) Phytoplankton Zooplankton Fish

(3) Grasses Chameleon Insects Birds

(4) Fallen leaves Bacteria Insect - Birds

4. An ecosystem is a complex interacting system of: (1) Populations (2) Individuals (3) Communities and their soil conditions (4) Communities and their physical environment

5. The slow rate of decomposition of fallen logs in nature is due to their (1) Low cellulose content (2) Low moisture content (3) Poor nitrogen content (4) Anaerobic environment around them

6. Consider the following statements concerning food chains a. Removal of 80% tigers from an area resulted in greatly increased growth of vegetation b. Removal of most of the carnivores resulted in an increased population of deers c. The length of food chains is generally limited to 3-4 trophic levels due to energy loss d. The length of food chains may vary from 2 to 8 trophic levels Which two of the above statements are correct? (1) a, b (2) b, c (3) c, d (4) a, d

7. The dominant second trophic level, in a lake ecosystem, is (1) Phytoplanktons (2) Zooplanktons (3) Benthos (4) Submerged rooted vegetation

8. If we completely remove the decomposers from an ecosystem, its functioning will be adversely affected, because

(1) Mineral movement will be blocked (2) The rate of decomposition will be very high (3) Energy flow will be blocked (4) Herbivores will not receive solar energy

9. In a biotic community, the primary consumers are (1) Detritivores (2) Herbivores (3) Carnivores (4) Omnivores

10. Which of the following pairs is a sedimentary type of biogeochemical cycle? (1) Phosphorus and nitrogen (2) Phosphorus and sulphur (3) Oxygen and nitrogen (4) Phosphorus and carbon



11. Which of the following is the most stable ecosystem? (1) Mountain (2) Ocean (3) Forest (4) Desert

12. The primary succession refers to the development of communities on a (1) Forest clearing alter devastating fire (2) Newly-exposed habitat with no record of earlier life form (3) Freshly cleared crop field (4) Pond freshly fifed with water after a dry phase

13. The 10% energy transfer law of food chain was given by (1) Lindemann (2) Tansley (3) Stanley (4) Weismann

14. Which of the following ecosystem has the highest gross primary productivity? (1) Mangroves (2) Rainforest (2) Grassland (4) Coral reef

15. Which of the following acts as ―nature's scavengers"? (1) Insects (2) Microorganisms (3) Man (4) Animals

16. In a terrestrial ecosystem such as forest, maximum energy is available at which trophic level?

(1) T3 (2) T4 (3) T1 (4) T2

17. The main role of bacteria in the carbon cycle involves (1) Chemosynthesis (2) Digestion or breakdown of organic compounds (3) Photosynthesis (4) Assimilation of nitrogenous compounds

18. The rate at which light energy is converted into chemical energy of organic molecules is the ecosystem's

(1) Net secondary productivity (2) Gross primary productivity (3) Net primary productivity (4) Gross secondary productivity

19. Energy transfer from one trophic level to other, in a food chain, is (1) 10% (2) 20% (3) 1% (4) 2%

20. Plant decomposers are (1) Monera and fungi (2) Fungi and plants (3) Protista and animalia (4) Animalia and monera

21. Bamboo plant is growing in a fir forest then what will be the trophic level of it? (1) First trophic level (2) Second trophic level (3) Third trophic level (4) Fourth trophic level

22. Which of the following is expected to have the highest value (gm/m2/yr) in a grassland ecosystem?

(1) Secondary production (2) Tertiary production (3) Gross production (GP) (4) Net production (NP)

23. An ecosystem which can be easily damaged but recover after some time if damaging effect stops will be having

(1) Low stability and high resilience (2) High stability and low resilience (3) Low stability and low resilience (4) High stability and high resilience



24. An ecosystem is: (1) The abiotic component of an area (2) A community of organisms interacting with one another (3) That part of Earth and its atmosphere where living organisms exist (4) A community of organisms together with the environment in which they live

25. Which one of the following is not used for construction of ecological pyramids? (1) Fresh weight (2) Dry weight (3) Number of individuals (4) Rate of energy flow

26. Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

(1) Frog (2) Phytoplankton (3) Fish (4) Zooplankton

27. The correct sequence of plants in a hydrosere is

(1) Oak Lantana Volvox Hydrilla Pistia Scirpus

(2) Oak Lantana Scirpus Pistia Hydrilla Volvox

(3) Volvox Hydrilla Pistia Scirpus Lantana Oak

(4) Pistia Volvox Scirpus Hydrilla Oak Lantana

28. The biomass available for consumption by the herbivores and the decomposers is called (1) Gross primary productivity (2) Net primary productivity (3) Secondary productivity (4) Standing crop

29. Which of the following representations shows the pyramid of numbers in a forest ecosystem?

(1) D (2) A (3) B (4) C

30. Which of the following is an ecosystem service provided by a natural ecosystem? (1) Pollutant absorption and reduction of the threat of global warming (2) Prevention of soil erosion (3) Cycling of nutrients (4) All of the above

31. In a tree ecosystem, pyramid of numbers is: (1) Inverted (2) Upright (3) Any of the two (4) None of these

32. During the process of ecological succession the changes that take place in communities are: (1) Random (2) Very quick (3) Orderly and sequential (4) Not influenced by the physical environment.

33. Climax community is in a state of: (1) Equilibrium (2) Disorder (3) Non-equilibrium (4) Constant change.



34. Grazing food chain (1) Provides inorganic matter to detritus food chain (2) Binds the inorganic nutrients into organic matter (3) Is based on energy present in detritus (4) Does not add energy into ecosystem

35. Among the following forest types, which one has the highest net primary productivity? (1) Tropical dry deciduous forests (2) Tropical rain forests (3) Coniferous forests (4) Subtropical forests

36. The amount of living matter present in a component population at any time in an ecosystem is called as

(1) Standing state (2) Standing quality (3) Standing crop (4) Immobilized nutrients

37. Which of the followings statement not correct about energy flow in an ecosystem? (1) Pyramid of energy is always upright (2) Energy flow is unidirectional (3) Energy flow is cyclic (4) Ecological efficiency is generally 10%

38. Climax communities (1) Are more diverse than pioneer communities (2) Are less stable than pioneer communities (3) Have a large entropy then pioneer communities (4) Have a large number but fewer species than pioneer communities

39. Pyramid of number in a cropland ecosystem is (1) Upright (2) Inverted (3) Rhomboidal (4) Spindle shaped

40. Which of the following phenomena does not play a significant role in the maintenance of homeostasis in an ecosystem?

(1) Carrying capacity (2) Biotic potential (3) Self regulation (4) Feedback

41. Vertical distribution of different species occupying different levels is called (1) Physiognomy (2) Phenology (3) Stratification (4) Phenotype

42. Climax community show

(1) 1P

ratioR

(2) 1P

ratioR

(3) P

ratio unityR

(4) P

ratio zeroR

43. Least productive ecosystem is (1) Grassland (2) Savannah (3) Forest (4) Tundra

44. Atmospheric input is negligible in (1) Carbon cycle (2) Phosphorus cycle (3) Oxygen cycle (4) Nitrogen cycle

45. In the hydrosere the reed-swamp stage is followed by (1) Marsh-meadow stage (2) Submerged free floating plant stage (3) Submerged plant stage (4) Phytoplankton

46. Annual net productivity of the whole biosphere is (1) 80 billion tons (2) 170 billion tons (3) 55 billion tons (4) 115 billion tons

47. Which of the following play an important role in the maintenance of the biogeochemical cycles in the ecosystem?

(1) Producers (2) Herbivores (3) Consumers (4) Decomposers



48. Which of the following is the logical sequence of carbon cycle?

(1) Photosynthesis Consumer Decomposer

(2) Photosynthesis Decomposer Consumer

(3) Consumer Photosynthesis Decomposer

(4) Decomposer Photosynthesis Consumer

49. Largest ecosystems in the world are: (1) Forests (2) Oceans (3) Great lakes (4) Grasslands

50. A predator (1) Is too efficient to overexploit its prey (2) Helps in maintaining species diversity by increasing the intensity of competition among

prey species. (3) Acts as conduits for energy transfer across trophic levels (4) Shows (+, +) interaction with its prey


1. The sequence of communities of primary succession in water is: (1) Phytoplankton, sedges, free-floating hydrophytes, rooted hydrophytes, grasses and

trees. (2) Phytoplankton, free-floating hydrophytes, rooted hydrophytes, sedges, grasses and

trees. (3) Free-floating hydrophytes, sedges, phytoplankton, rooted hydrophytes, grasses and

trees. (4) Phytoplankton, rooted submerged hydrophytes, floating hydrophytes, reed swamp,

sedges, meadow and trees

2. Read the following statements and select the correct option w.r.t. population attributes (1) Population density is necessarily measured in numbers (2) Tiger census is often based on pug marks and fecal pellets (3) Biomass is a not a meaningful measure to know population size. (4) Size of a population for any species is not a static parameter (1) 1 & 2 (2) 1 & 4 (3) 3 & 4 (4) 2 & 4

3. The number of individuals of a species in a particular ecosystem at a given time remains constant due to:

(1) Man (2) Predators (3) Parasites (4) Available food

4. Which of the following type of ecosystem is expected in an area where evaporation exceeds precipitation, and mean annual rainfall is below 100mm:

(1) Desert (2) Grassland (3) Mangrove (4) Shrubby forest

5. A natural ecosystem: (1) Is auto-operated (2) Depends on man (3) Depends on plants (4) Depends on animals

6. Decomposers like fungi and bacteria are: i. Autotrophs ii. Heterotrophs iii. Saprotrophs iv. Chemo-autotrophs Choose the correct answer: (1) i and iii (2) i and iv (3) ii and iii (4) i and ii



7. Among the following, where do you think the process of decomposition would be the fastest? (1) Antarctic (2) Alpine region (3) Dry arid region (4) Tropical rain forest

8. An organism that feeds on dead organic matter other than bacteria or fungi is called: (1) Producer (2) Consumer (3) Detritivore (4) Decomposer

9. The process of mineralisation by microorganisms helps in the release of: (1) Inorganic nutrients from humus (2) Both organic and inorganic nutrients from detritus (3) Organic nutrients from humus (4) Inorganic nutrients from detritus and formation of humus.

10. An ecosystem must have continuous, external source of: (1) Food (2) Energy (3) Minerals (4) All of these

11. Which one of the following components of ecosystem comes from outside? (1) Energy (2) Oxygen (3) Insects (4) Temperature

12. In an ecosystem, the function of the producers is to: (1) Release energy (2) Utilize chemical energy (3) Convert organic compounds into inorganic compounds (4) Trap solar energy and convert it into chemical energy

13. Importance of ecosystem lies in: (1) Cycling of materials (2) Flow of energy (3) Both of these (4) None of these

14. The major functional processes of an ecosystem are: (1) Energy flow and food chain (2) Food chain and decomposers (3) Energy flow and decomposers (4) Mineral recycling and energy flow

15. The correct path of energy flow in ecosystem is:

(1) Producers herbivores carnivores decomposers

(2) Producers carnivores herbivores decomposers

(3) Herbivores carnivores producers decomposers

(4) Herbivores producers carnivores decomposers

16. If all green plants on the Earth are destroyed: (1) All pests shall die (2) All animals shall die ultimately (3) Nothing shall happen to animals (4) Only herbivorous animals shall die

17. The transfer of energy from organisms to organisms in a natural community establishes: (1) Natural barriers (2) Food chains (3) Biological control (4) All of these

18. Food chain is: (1) Transfer of chemical energy- from producers to consumers (2) A number of human beings forming a chain for food (3) Animals near a source of food (4) None of the above

19. In a food chain, as we go from lower to higher trophic level, the energy: (1) Becomes doubled at each step (2) Increases irregularly (3) Remains constant (4) Decreases



20. Food chains occur only in the: (1) Sea (2) Forests (3) Deserts (4) In all of these places

21. Which of the following is a correct food chain?

(1) Eagle Snake Grasshopper Grass Frog

(2) Frog Snake Eagle Grasshopper Grass

(3) Grasshopper Grass Snake Frog Eagle

(4) Grass Grasshopper Frog Snake Eagle .

22. The food chain in which microorganisms break down the energy rich compounds synthesized by producers, is called:

(1) Ecosystem (2) Predator food chain (3) Detritus food chain (4) Parasitic food chain

23. In a tiger reserve, the tiger is placed in the: (1) Apex of the food chain (2) Bottom of the food chain (3) Core of the reserve forest (4) Centre of complex food web

24. In a pond ecosystem, the food chain starts with: (1) Small fishes (2) Aquatic insects (3) Zooplankton (4) Phytoplankton

25. A food chain begins with: (1) Nitrogen fixation (2) Carbon dioxide fixation (3) Carbohydrate metabolism (4) Decomposition of dead substances

26. The first link in any food chain is green plants because: (1) They are firmly fixed to soil (2) They are widely distributed (3) They alone have the capacity to fix the atmospheric CO2 in the presence of sunlight (4) There are more herbivorous animals than carnivores 27. When man eats fish, which feeds on zooplankton, which have eaten small plants, the

producer in the chain is: (1) Fish (2) Man (3) Small plants (4) Zooplankton

28. 1. Plant 2. Rabbit 3. Fox and 4. Lion are the components of a food chain. In this food chain, the maximum energy will be found in:

(1) 3 (2) 4 (3) 2 (4) l

29. Food levels in an ecosystem are called: (1) Trophic levels (2) Consumer levels (3) Producer levels (4) Herbivore levels

30. Which of the following is not a producer? (1) Nostoc (2) Volvox (3) Agaricus (4) Spirogyra

31. If the carbon atoms fixed by producers already have passed through three species, the trophic level of the last species; would be.

(1) Scavenger (2) Tertiary producer (3) Tertiary consumer (4) Secondary consumer

32. Graphic representation of biomass relationship between the producer and consumer in an ecosystem is called:

(1) Ecological system (2) Trophic levels (3) Ecological niche (4) Ecological pyramid



33. The pyramid of numbers deals with the number of: (1) Species in a given area (2) Subspecies in a community (3) Individuals in a community (4) Individuals in a trophic level

34. Which of the following cycles would be affected if decomposers of an ecosystem vanish? (1) Producer's cycle (2) Consumer's cycle (3) Decomposer's cycle (4) Biogeochemical cycle

35. Among the following biogeochemical cycles which one does not have losses due to respiration?

(1) Sulphur (2) Nitrogen (3) Phosphorus (4) All of the above

36. The number of primary producers within a specified area would be maximum in: (1) Desert (2) Forest ecosystem (3) Pond ecosystem (4) Grassland ecosystem

37. Productivity is the rate of production of biomass expressed in terms of: i. (kcal nr–3) yr–1 ii. gr2 yr–1 iii. g–1 yr–1 iv. (kcal m–2) yr–1 (1) ii (2) iii (3) i and iii (4) ii and iv

38. The greatest biomass of autotrophs in the world's oceans is that of: (1) Free-floating micro-algae, cyanobacteria and nanoplankton (2) Benthic brown algae, coastal red algae and daphnids (3) Benthic diatoms and marine viruses (4) Sea grasses and slime moulds

ASSERTION & REASON QUESTIONS(CLASS WORK)








1. A: Lichens and mosses are said to form the pioneer community in xerarch succession.

R: It is because these species get established later, during the course of succession.

2. A: Community organisation, food chains and food web are complex in both seral and climax stages.

R: Seral and Climax stages are similar in structure and functions.

3. A: Xerosere is a type of succession

R: It starts in water.

4. A: Primary succession takes a very long time.

R: Succession taking place after forest fire is called primary succession.



5. A: In a food chain members of successive higher levels are fewer in number. R: Number of organisms at any trophic level depends upon the availability of organisms

which serve as food at the lower level.

6. A: A network of food chains existing together in an ecosystem is known as a food web. R: An animal-like kite cannot be a part of a food web.

7. A: Energy pyramid is erect. R: The energy of one trophic level is lower than another level as we go up.

8. A: Ecotone shows more diversity. R: Ecotone is a sharp transition zone between two or more diverse communities. 9. A: Net primary productivity is gross primary productivity minus respiration. R: Secondary productivity is produced by heterotrophs. 10. A: Food web consists of several food chains. R: Food web decreases the stability of an ecosystem. 11. A: Ecological pyramids are also called Eltonian pyramids. R: An ecological pyramid is always upright.

12. A: The pyramids of number, biomass and energy is always upright. R: It happens because the producers always outnumber and outweigh the herbivores which

in turn always outnumber and outweigh the carnivores.

13. A: The plant biomass which serves as the food of herbivores and decomposers is said to result from the gross primary productivity.

R: Gross primary productivity is the rate of total production of organic material (biomass). 14. A: Pyramid of energy may be upright or inverted. R: Only 10% of energy goes to next trophic level. 15. A: The conversion of productivity at next trophic level is 10%. R: Energy is lost in the respiration process.



PREVIOUS YEARS QUESTIONS(HOME WORK)

1. Identify the possible link ―A‖ in the following food chain: (AIPMT 2012)

Plant insect frog ―A‖ Eagle (1) Parrot (2) Rabbit (3) Wolf (4) Cobra

2. The upright pyramid of number is absent in: (AIPMT 2012) (1) Grassland (2) Pond (3) Tree (4) Lake

3. Given below is an imaginary pyramid of numbers. What could be one of the possiblities about certain organisms at some of the different levels? (AIPMT 2012)

10

50

500

1

TC

SC

PC

PP

(1) Level PC is ―rats‖ and level SC is ―cats‖ (2) Level PC is ―insects‖ and level SC is ―small insectivorous birds‖ (3) Level PP is ―phytoplanktons‖ in sea and ―Whale‖ on top level TC (4) Level one PP is ―pipal trees‖ and the level SC is ―sheep‖.

4. Which one of the following is not a functional unit of an ecosystem? (AIPMT 2012) (1) Stratification (2) Energy flow (3) Decomposition (4) Productivity

5. The rate of formation of new organic matter by rabbit in a grassland, is called (AIPMT 2012) (1) Net productivity (2) Secondary productivity (3) Net primary productivity (4) Gross primary productivity

6. Identify the likely organisms (1), (2), (3) and (4) in the food web shown below: (AIPMT 2012)

option:

(1) (2) (3) (4)

(1) deer rabbit frog rat

(2) dog squirrel bat deer

(3) rat dog tortoise crow

(4) squirrel cat rat pigeon

7. The breakdown of detritus into smaller particles by earthworm is a process called: (CBSE Mains 2011) (1) Catabolism (2) Humification (3) Fragmentation (4) Mineralization



8. The flow of energy in the ecosystem is: (Orissa JEE 2011) (1) Cyclic (2) Bidirectional (3) Unidirectional (4) Multidirectional

9. Ecosystem creates: (PCS 2004; MPPMT 2011) (1) Food chain (2) Food web (3) Both of these (4) None of these

10. In grazing food chain, carnivores may also be referred to as: (Kerala PMT 2011) (1) Primary producers (2) Secondary producers (3) Primary consumers (4) Secondary consumers

11. Which of the following statements regarding food chain is false? (Kerala PMT 2011)

(1) In an aquatic system, grazing food chain is the major conduit for energy flow

(2) In terrestrial ecosystems, a large fraction of energy flows through detritus food chain

(3) The detritus food chain begins with dead organic matter

(4) Primary consumers belong to the first trophic level

12. Which of the following groups is absolutely essential functional component of the ecosystem?

(1) Producers (2) Detritivores (DUMET 2011) (3) Producers and herbivores (4) Producers and detrivores

13. Which one of the following animals may occupy more than one trophic levels in the same ecosystem at the same time? (CBSE Mains 2011)

(1) Frog (2) Sparrow (3) Lion (4) Goat

14. Which one of the following is a primary consumer? (BHU 2002; Orissa JEE 2011) (1) Carnivore (2) Herbivore (3) Producer (4) None of these

15. Mass of living matter at a trophic level in an area at any time is called: (CBSE 2011) (1) Detritus (2) Humus (3) Standing state (4) Standing crop

16. Standing crop refers to: (JKCMEE 2011) (1) All the living forms in an area (2) All the crop plants in an area (3) All the photosynthetic living forms in an area (4) The amount of living matter in a component population of an ecosystem at any time

17. Which pyramid is always upright, can never be inverted? (CPMT 2010; HPPMT 2011) (1) Pyramids of energy (2) Pyramids of biomass (3) Pyramids of number (4) Pyramids of dry biomass 18. Which one of the following statements for pyramid of energy is incorrect whereas remaining

three are correct? (CBSE 2011) (1) Its base is broad (2) It is upright in shape (3) It is inverted in shape (4) It shows energy content of different trophic level organisms

19. Which one of the following statements is correct for secondary succession? (CBSE 2011) (1) It begins on a bare rock (2) It occurs on a deforested site (3) It follows primary succession (4) It is similar to primary succession except that it has relatively fast pace



20. Select the correct match: 1 Sedimentary nutrient cycle Nitrogen cycle 2 Pioneer species Lichens 3 Secondary succession Burned forests 4 Pyramid of biomass in sea Upright (Kerala PMT 2011) (1) 1, 2 and 4 only (2) 1 and 3 only (3) 2 and 3 only (4) 2 and 4 only

21. Which one of the following is the sedimentary cycle? (Kerala PMT 2001; HPPMT 2006,11) (1) Carbon cycle (2) Oxygen cycle (3) Hydrogen cycle (4) Phosphorus cycle

22. The biomass available for consumption by the herbivores and the decomposers is called: (CBSE 2010)

(1) Standing crop (2) Secondary productivity (3) Net primary productivity (4) Gross primary productivity

23. Which of the following statements regarding decomposition is false? (Kerala PMT 2010) (1) Earthworm is a detritivore (2) Detritus is the raw material for decomposition (3) Warm and moist environment favours decomposition (4) Precipitation of soluble inorganic nutrients into the soil horizon as unavailable salt is

called mineralization

24. The "10 per cent law" is related to: (DUMET 2010) (1) Mendelian genetics (2) Non-Mendelian genetics (3) Energy transfer from lower trophic level to higher trophic level (4) Energy consumption during photosynthesis in C4 plants

25. Study the four statements (1-4) given below and select the two correct ones out of them: 1. A lion eating a deer and a sparrow feeding on grain are ecologically similar in being

consumers. 2. Predator starfish Pisaster helps in maintaining species diversity of some invertebrates. 3. Predators ultimately lead to the extinction of prey species. 4. Production of chemicals such as nicotine, strychnine by the plants are metabolic

disorders. The two correct statements are: (CBSE 2010) (1) l and 2 (2) l and 4 (3) 2 and 3 (4) 3 and 4

26. The pyramid of energy is always: (AMU 2010; AFMC 2010) (1) Inverted (2) Upright (3) Both upright and inverted (4) Inverted in forest ecosystem

27. In primary succession on rocks, the pioneer species are usually: (DUMET2010) (1) Algae (2) Fungi (3) Lichens (4) Bryophytes

28. Biogeochemical cycling means cycling of: (AMU 2010) (1) Water (2) Energy in an ecosystem (3) Nutrients in an ecosystem (4) Gases between plants and the atmosphere

29. Some of the nutrient cycles are labelled as below. 1. Sulphur cycle 2. Phosphorus cycle, 3. Carbon cycle and 4. Nitrogen cycle. Of these, the sedimentary cycle is represented by: (Kerala PMT 2010) (1) 1 only (2) 2 only (3) 3 only (4) l and 2 only



30. Which of the following is an example of man-made ecosystem? (WB. JEE 2009) (1) Forest (2) Aquarium (3) Herbarium (4) Tissue culture

31. Which most often limits the primary productivity of the ecosystem? (Orissa JEE 2009) (1) Oxygen (2) Nitrogen (3) Consumers (4) Solar radiation/Light

32. Identify the correct type of food chain.

Dead animal Blowfly maggots Common frog Snake: (WB. JEE 2009) (1) Grazing food chain (2) Detrital food chain (3) Predator food chain (4) Decomposer food chain

33. Trophic levels in ecosystem is formed by: (WB. JEE 2009) (1) Only plants (2) Only bacteria (3) Only herbivorous (4) Organisms linked in food chain

34. In an aquatic ecosystem, the trophic level equivalent to cows in grasslands is: (DUMET2009) (1) Nekton (2) Benthos (3) Phytoplankton (4) Zooplankton

35. Which one of the following types of organisms occupy more than one trophic level in a pond ecosystem?

(1) Fish ' (2) Frog (CBSE 2009) (3) Zooplankton (4) Phytoplankton

36. Pyramid of energy in a river ecosystem is: (AFMC 2009) (1) Constant (2) Declining (3) Always upright (4) Always erect

37. A progressive series of changes in plant and animal life of an area from initial colonization is known as:

(1) Selection (2) Evolution (AMU 2009) (3) Specialization (4) Succession

38. Which are the first organisms to colonize on a bare rock? (Orissa JEE 2009) (1) Fungi (2) Mosses (3) Lichens (4) Diatoms

39. The final stable community in ecological succession is: (DUMET 2009) (1) Sere (2) Climax (3) Pioneers (4) Carnivores

40. A man-made ecosystem is: (Uttarakhand PMT 2008) (1) Less in diversity (2) More in diversity (3) Man does not make ecosystem (4) More stable than natural ecosystem

41. Which of the following ecosystem has very little primary productivity? (Orissa JEE 2008) (1) Sea (2) River (3) Forest (4) Grassland

42. Identify which one of the following is an example of incomplete ecosystem? (WB. JEE 2008) (1) Cave (2) River (3) Wetland (4) Grassland

43. Which of the following is expected to have the highest value (g/m2/yr) in a grassland ecosystem? (AFMC 2008)

(1) Net Production (NP) (2) Secondary Production (3) Tertiary Production (4) Gross Production (GP)

44. Most diverse organism of an ecosystem is: (JCECE 2008) (1) Producer (2) Consumer (3) Carnivores (4) Decomposer



45. Decomposition of organic matter is brought about by: (JKCMEE2008) (1) Plants (2) Protozoans (3) Microorganisms (4) None of these

46. Which of the following organisms form the decomposers? (BV Pune 2007; Manipal 2008) (1) Pteris (2) Bacteria (3) Saprophytic fungi (4) Both (2) and (3)

47. Which of the following groups of organisms are ecologically similar? (EAMCET2008) (1) Producer protists and Consumer protists (2) Monerans and Producer protists (3) Consumer protists and Fungi (4) Monerans and Fungi

48. A detrivorous animal of economic importance is: (Karnataka CET 2008) (1) Leech (2) Earthworm (3) Giriraja fowl (4) Caterpillar larva

49. In an ecosystem: (AIEEE 2004; JKCMEE 2008) (1) Movement of energy is unidirectional (2) Cycling of energy is an independent process (3) Macro and micronutrients cycle at the same pace (4) Cycling of energy and nutrients is a coupled process

50. The average trophic efficiency of transfer of energy from one trophic level to the higher trophic level is called: (EAMCET2008)

(1) Assimilation efficiency (2) Exploitation efficiency (3) Gross primary production (4) Lindeman's trophic efficiency rule

51. Approximately how much of the chemical energy within producer tissue becomes chemical energy within herbivore tissue? (CPMT2008)

(1) 01% (2) 30% (3) 10% (4) 90%

52. Which of the following processes does not affect the nutrient flow in an ecosystem? (Orissa JEE 2008) (1) Migration (2) Parasitism (3) Predation (4) Production

53. Which one of the following shows detritus food chain? (DPMT2008)

(1) Organic waste Bacteria Molluscs (2) Plankton Small fishes Large fishes

(3) Grass Insects Snakes (4) All of the above

54. Consider the following statements concerning food chams. (CBSE2008) 1. Removal of 80% tigers from an area resulted in greatly increased growth of the

vegetation. 2. Removal of most of the carnivores resulted in an increased population of deers. 3. The length of the food chains is generally limited to 3-4 trophic levels due to energy

loss. 4. The length of food chains may vary from 2 to 8 trophic levels. (1) land 2 (2) 2 and 3 (3) 3 and 4 (4) land 4

55. In an ecosystem, bacteria are: (VMMC-Safdarjung 2008) (1) Microconsumers (2) Macroconsumers

(3) Primary consumers (4) Secondary consumers



56. Stability of ecosystem depends upon: (CPMT 2007; BCECE2008) (1) Primary productivity (2) Number of producers

(3) Number of consumers (4) Exchange between producers and consumers

57. Extinction of a species in a food chain is compensated by: (CPMT 2007; JCECE 2008) (1) Food web (2) Food chain (3) Ecological pyramid (4) None of these

58. Which one of the following is not used for construction of ecological pyramids? (CBSE 2006; AFMC 2008) (1) Dry weight (2) Fresh weight (3) Rate of energy flow (4) Number of individuals

59. Which type of pyramid of energy is inverted? (Orissa JEE 2008) (1) Tree (2) Grassland (3) Both of these (4) None of these

60. In which of the following cycles, does the reservoir of the nutrient exist in material form? (1) Water cycle (2) Carbon cycle (VTTEEE2008) (3) Phosphorus cycle (4) Nitrogen cycle

61. Which of the following are reservoirs for phosphorus and nitrogen cycle respectively? (Gujarat GET 2008) (1) Consumers (2) Bedrocks and Atmosphere (3) Atmosphere and Bedrocks (4) Atmosphere and Producers

62. The term ecosystem was coined by: (BHU 2007; VMMC-Safdarjung 2007) (1) Reiter (2) Odum (3) Tansley (4) Ernst Haeckel

63. Ecosystem has two components: (PCS 2005; BCECE 2007) (1) Plants and animals (2) Biotic and abiotic (3) Weeds and trees (4) None of these

64. Pond is an example of: (PMT 2007) (1) Forest ecosystem - (2) Natural ecosystem (3) Artificial ecosystem (4) Grassland ecosystem

65. Sequence of species through which the organic molecules in a community passes is called: (1) Ecosystem (2) Food chain (Orissa JEE 2007) (3) Population (4) Ecological pyramid

66. Which of the following is the correct sequence in the food chain?(Pb. PMT 2004; AMU 2007)

(1) Grass Wolf Deer Buffalo (2) Grass Snake Insect Deer

(3) Grass Insect Bird Snake (4) Bacteria Grass Rabbit Wolf

67. Detritus food chain starts from: (Orissa JEE 2007) (1) Virus (2) Algae (3) Protozoa (4) Bacteria

68. Peacock cats a snake and snake eats frog and frog eats insect while insect eats green plant, then position of peacock is: (RPMT 2005; VMMC-Safdarjung 2007)

(1) Decomposer (2) Primary producer (3) Secondary producer (4) Top at the apex of food pyramid



69. In a pyramid of numbers in a grassland ecosystem, the large population is that of: (Kerala PMT 2007) (1) Producers (2) Herbivores (3) Primary consumers (4) Tertiary consumers

70. Which one of the following regarding ecological pyramid is ' not correct‘? (Kerala PMT 2007) (1) In most ecosystems, the pyramid of numbers and biomass are upright (2) In deep water ecosystem, the pyramid of biomass is upright (3) In tree-dominated ecosystem, the pyramid of numbers is inverted (4) The pyramid of energy expresses mainly the rate of food production

71. Pyramid of energy in a pond ecosystem is always: (CPMT2007) (1) Linear (2) Upright (3) Irregular (4) Inverted

72. The pyramid of energy in a forest ecosystem is: (WB.JEE 2007) (1) Always upright (2) Always inverted (3) Both (1) and (2) (4) None of these

73. A place was rocky and barren but now, there is a green forest; the sequence of origin is: (RPMT 2005;VMMC-Safdarjung 2007)

(1) Lichen, moss, herbs, shrubs (2) Moss, lichen, herbs, shrubs (3) Lichen, moss, shrubs, herbs (4) Shrubs, herbs, moss, lichen

74. An ecosystem which can be easily damaged but can recover after some time if damaging effect stops will be having: (CBSE 2004; Manipal 2007)

(1) High stability and Low resilience (2) Low stability and Low resilience (3) High stability and High resilience (4) Low stability and High resilience

75. Area where two ecosystems overlap each other: (Kerala PMT 2004; DPMT 2006) (1) Niche (2) Ecotone (3) Ecotype (4) Edge line

76. The natural cycling of carbon between organisms and their environment is directly\accomp -lished through: (Uttarakhand PMT 2006)

(1) Photosynthesis and respiration (2) Radiations of solar energy (3) Nutrition and excretion (4) All of the above

77. In a climax community: (HPPMT2006) (1) Size of individual is small (2) Efficiency of energy use is low (3) Food chain and food web is complex (4) Ecological niches are few generalised compared to adjoining communities

78. Lichen is the pioneer vegetation of which succession? (BHU 2006) (1) Lithosphere (2) Xerosere (3) Hydrosere (4) Psammosere

79. Primary succession occurs in: (AMU 2006) (1) Previously unoccupied area (2) Previously occupied area (3) Both of the above (4) None of the above

80. The zooplanktonic forms are: (WB. JEE 2006) (1) Carnivores (2) Primary producers (3) Primary consumers (4) Secondary consumers

81. Food chain is a series of population which starts with producers. It is concerned with: (AFMC 2006; JCECE 2007) (1) Energy flow and transfer of nutrients (2) Biotic components only (3) Biotic components and decomposers (4) Both (1) and (2)



82. During food chain, the maximum energy is stored in: (RPMT 2006) (1) Producers (2) Herbivores (3) Carnivores (4) Decomposers

83. Driving force of ecosystem is: (WB. JEE 2006) (1) Biomass (2) Producer (3) Solar energy (4) Carbohydrate in plants

84. Decomposers are; (BHU 2006) (1) Autotrophs (2) Heterotrophs (3) Organotrophs (4) Autoheterotrophs

85. The storage of energy at consumer level is known as: (Manipal 2006) (1) Net productivity (2) Secondary productivity (3) Net primary productivity (4) Gross primary productivity

86. The force operating in an ecosystem which opposes the unchecked growth of population is: (1) Mortality (2) Fecundity (VMMC-Safdarjung 2006) (3) Biotic control (4) Environmental resistance

87. If we completely remove the decomposers from an ecosystem, the ecosystem functioning will be adversely affected because: (BHU 2003; Pb. PMT 2005)

(1) Energy flow will be blocked (2) Mineral movement will be blocked (3) Herbivore will not receive solar energy (4) Rate of decomposition of other components will be very high

88. The ultimate source of energy in an ecosystem is: (CPMT 2001; RPMT 2004,05) (1) ATP (2) Glucose (3) Sunlight (4) Nucleic acid

89. Approximately what amount of energy is available to one trophic level from one level lower to it?

(1) 10% (2) 01% (PCS 2002; AMU 2005; BHU 2005) (3) 20% (4) 30%

90. Inverted pyramid is found in: (Manipal 2005) (1) Energy pyramid of grassland (2) Biomass pyramid of grassland (3) Biomass pyramid of aquatic system (4) Pyramid of number of aquatic system

91. The pyramid of biomass in a pond ecosystem is: (VMMC-Safdarjung 2004; BCECE 2005) (1) Inverted (2) Always upright (3) Sometimes upright (4) Upright and sometimes inverted

92. The pyramid of energy is always upright for any ecosystem. This situation indicates the fact that:

(1) Producers have the lowest energy conversion efficiency (Karnataka CET 2005) (2) Carnivores have a better energy conversion efficiency than herbivores (3) Energy conversion efficiency is the same in all trophic levels (4) Herbivores have a better energy conversion efficiency than carnivores

93. A sedimentary type of biogeochemical cycle is: (PCS 2004) (1) Carbon cycle (2) Sulphur cycle (3) Nitrogen cycle (4) Hydrologic cycle

94. Last stable community in succession which depends on climate is: (DPMT2004) (1) Seral community (2) Climax community (3) Both (1) and (2) (4) None of these



95. In a food chain, the total amount of living material is depicted by: (Pb. PMT 2004) (1) Pyramid of biomass (2) Trophic levels (3) Pyramid of number (4) Pyramid of energy

96. When the number of organisms at successive levels are plotted they assume the shape of a pyramid. This is called the pyramid of: (VMMC-Safdarjung 2004)

(1) Biomass (2) Number (3) Energy (4) None of these

97. In food web, hyaenas and vultures are: (MPPMT2004) (1) Predators (2) Scavengers (3) Decomposers (4) Primary consumers

98. Ecological pyramids were first devised by: (CBSE 2000; RPMT 2004) (1) Charles Elton (2) R. Hesse (3) R. A. Lindeman (4) Justus von Liebig

99. The minimum number of components required for an ecosystem to survive: (Kerala PMT 2004)

(1) Producer and decomposer (2) Producer and primary consumer (3) Primary and secondary consumer (4) Producer and secondary consumer

100. These belong to the category of primary consumers: (Karnataka CET 2004) (1) Snakes and frogs (2) Water insects (3) Insects and cattle (4) Eagle and snakes

101. Ecosystem contains: (Pb. PMT 2004) (1) Producers (2) Consumers (3) Decomposers (4) All of these

102. In a food chain, lion is a: (VMMC-Safdarjung 2004) (1) Secondary consumer (2) Primary consumer (3) Tertiary consumer (4) Secondary producer

103. Percentage of energy transported from primary producer to herbivores in an ecosystem is: (1) 0% (2) 20% (JCECE 2003; AIEEE 2004) (3) 10% (4) 50%

104. Bacteria and fungi in a forest ecosystem are generally: (Kerala PMT 2004) (1) Producers (2) Decomposers (3) Primary consumers (4) Secondary consumers

105. Ecosystem is not a/an: (Orissa JEE 2004) (1) Open system (2) Closed system (3) Variable system (4) None of these

106. Which of the following is the most stable ecosystem? (RPMT 2004) (1) Desert (2) Forest (3) Ocean (4) Mountain

107. The Great Barrier Reef along the east coast of Australia.can be categorized as: (1) Biome (2) Ecosystem (AIIMS 2004) (3) Population (4) Community

108. In a comparative study of grassland ecosystem and pond ecosystem it may be observed that:

(1) The biotic components are almost similar (Karnataka CET 2003) (2) The abiotic components are almost similar (3) Primary and secondary consumers are similar (4) Both biotic and abiotic components are different



109. The rate of conversion of light energy into chemical energy or organic molecules in an ecosystem is: (Kerala PMT 2003)

(1) Net primary productivity (2) Gross primary productivity

(3) Net secondary productivity (4) Gross secondary productivity

110. Which of the following ecosystems has the highest gross primary productivity? (DPMT 2003) (1) Grasslands (2) Coral reefs (3) Mangroves (4) Tropical rain forests

111. In a food chain, herbivores are: (Manipal 2003) (1) Decomposers (2) Primary producers (3) Primary consumers (4) Secondary consumers

112. Energy and nutrients enter a community through: (CPMT 2003) (1) Producers (2) Herbivores (3) Carnivores (4) Decomposers

113. Mr. X is eating curd/yoghurt. For this food intake in a food chain he should be considered as occupying: (AIIMS 2003)

(1) First trophic level (2) Second trophic level (3) Third trophic level (4) Fourth trophic level

114. In the phosphorus cycle, weathering makes phosphate available first to: (AMU 2002) (1) Producers (2) Decomposers (3) Consumers (4) None of these

115. Which of the following pyramid of numbers in ecology is not upright? (Orissa JEE 2002) (1) Pond ecosystem (2) Desert ecosystem (3) Tree ecosystem (4) Forest ecosystem

116. A bamboo plant is growing in a forest. What will be its trophic level? (CBSE 2002) (1) First trophic level (T1) (2) Second trophic level (T2) (3) Third trophic level (T3) (4) Fourth trophic level (T4)

117. The statement "Tiger is the apex of food chain" indicates: (Orissa JEE 2002) (1) Tiger is carnivorous (2) Tiger has many enemies (3) Tiger has maximum biomass (4) Tiger is dependent upon large number of herbivores and even more number of trees in

forest

118. Saprophytes in an ecosystem belongs to: (Orissa JEE 2002) (1) Producer component (2) Herbivore component (3) Carnivore component (4) Decomposer component

119. The total energy fixed by a green plant of an ecosystem on the whole is called: (PCS 2001) (1) Primary production (2) Secondary production (3) Gross production (4) None of these

120. Which of the following is correct about food chain? (AMU 2001)

(1) Zooplankton Phytoplankton Fishes

(2) Phytoplankton Fishes Zooplankton

(3) Phytoplankton Zooplankton Fishes (4) None of the above



121. Biological equilibrium is an equilibrium among the: (BCECE 2001) (1) Producers (2) Producers and consumers (3) Producers and decomposers (4) Producers, consumers and decomposers

122. Which are the biotic components of forest ecosystem? (MPPMT2001) (1) Producers (2) Consumers (3) Decomposers (4) All of these

123. The pyramid of numbers of a parasitic food chain in a forest ecosystem is: (PCS 2001) (1) Always upright (2) Always inverted (3) Mixture of inverted and upright (4) Sometimes inverted and sometimes upright

124. This is an inverted pyramid: (Karnataka CET2001) (1) Pyramid of energy in a pond ecosystem (2) Pyramid of biomass in a pond ecosystem (3) Pyramid of biomass in a grassland ecosystem (4) Pyramid of numbers in a grassland ecosystem

125. The presence of large amount of nitrogen in the atmosphere is due to: (AFMC2001) (1) Nitrites (2) Ammonia (3) Decomposers (4) Nitrogen cycle

126. Most food chains are composed of: (BHU2001) (1) 1 or 2 species (2) 3 or 4 species (3) 9 or 10 species (4) More than 16 species

127. If phytoplanktons are destroyed from sea, then: (MPPMT2000) (1) Algae will get more space to grow (2) Primary consumers will grow luxuriantly (3) Food chain will be affected (4) No effect will be seen

128. Which one of the following is source of energy to an ecosystem? (MPPMT2000) (1) ATP (2) Solar energy (3) Sugar stored (4) Heat liberated during respiration

129. The energy sources for omnivores are: (PCS 2000) (1) Primary producers and primary consumers (2) Primary consumers and secondary consumers (3) Primary producers, carnivores and decomposers (4) Primary producers , consumers and carnivores

130. Arrange the following ecosystems in terms of their increasing productivity: 1. Grassland 2. Open ocean 3. Desert 4. Tropical rain forest Select the correct answer code using the codes given below: Answer codes: (PCS 2000) (1) 3,2,1, 4 (2) 1,2,3,4 (3) 3,1,2, 4 (4) 4,1,2,3

131. Which one of the following always have steeper slope? (Har. PMT 2000) (1) Pyramid of biomass (2) Pyramid of energy (3) Pyramid of number (4) None of these

132. Secondary productivity is rate of formation of new organic matter by (NEET 2013) (1) Decomposer (2) Producer (3) Parasite (4) Consumer



133. The tendency of population to remain in genetic equilibrium may be disturbed by

(1) Lack of random mating (2) Random mating (NEET 2013)

(3) Lack of migration (4) Lack of mutations

134. Which one of the following processes during decomposition is correctly described?

(1) Leaching – Water soluble inorganic nutrients rise to the top layers of soil. (NEET 2013)

(2) Fragmentation – Carried out by organisms such as earthworm

(3) Humification – Leads to the accumulation of a dark coloured substance humus which undergoes microbial action at a very fast rate.

(4) Catabolism – Last step in the decomposition under fully anaerobic condition.

135. If 20J of energy is trapped at producer level, then how much energy will be available to peacock as food in the following chain? (AIPMT2014)

plant mice snake peacock

(1) 0.2J (2) 0.0002 J (3) 0.02 J (4) 0.002 J

136. Match the following and select the correct option: (AIPMT2014) (1) Earth worm (i) Pioneer species (2) Succession (ii) Detrivore (3) Ecosystem service (iii) Natality (4) Population growth (iv) Pollination (1) (2) (3) (4) (1) (iii) (ii) (iv) (i) (2) (ii) (i) (iv) (iii) (3) (i) (ii) (iii) (iv) (4) (iv) (i) (iii) (ii)

137. Given below is a simplified model of phosphorus cycling in a terrestrial ecosystem with four blanks (A-D). Identify the blanks. (AIPMT2014)

Consumers

Soil solution

C

Uptake

Run off

B

A B C D

(1) Detritus Rock minerals Producer Litter fall

(2) Producers Litter fall Rock minerals Detritus

(3) Rock minerals Detritus Litter fall Producers

(4) Litter fall Producers Rock minerals Detritus

138. Most animals are tree dwellers in a: (AIPMT 2015) (1) Thorn woodland (2) Temperate deciduous forest (3) Tropical rain forest (4) Coniferous forest



139. Vertical distribution of different species occupying different levels in a biotic community is known as: (AIPMT 2015) (1) Stratification (2) Zonation (3) Pyramid (4) Divergence 140. The mass of living material at a trophic level at a particular time is called: (AIPMT 2015) (1) Standing state (2) Net primary productivity (3) Standing crop (4) Gross primary productivity 141. In an ecosystem the rate of production of organic matter during photosynthesis is termed as: (AIPMT 2015) (1) Gross primary productivity (2) Secondary productivity (3) Net productivity (4) Net primary productivity 142. Secondary Succession takes place on / in: (AIPMT 2015) (1) Degraded forest (2) Newly created pond (3) Newly cooled lava (4) Bare rock 143. Which of the following would appear as the pioneer organisms on bare rocks? (NEET I- 2016)

(1) Green algae (2) Lichens (3) Liverworts (4) Mosses

144. Which one of the following is a characteristic feature of cropland ecosystem? (NEET I- 2016) (1)Ecological succession (2) Absence of soil organisms (3)Least genetic diversity (4) Absence of weeds 145. The term ecosystem was coined by (NEET I- 2016)

(1) E. Warming (2) E.P. Odum (3) A.G. Tansley (4) E. Haeckel

146. The primary producers of the deep-sea hydrothermal vent ecosystem are (NEET II- 2016) (1) Green algae (2) Chemosynthetic bacteria (3) Blue-green algae (4) Coral reefs



EXERCISE # LEVEL–I(CLASS WORK)

1. (4) 2. (4) 3. (2) 4. (4) 5. (2) 6. (2) 7. (2) 8. (1)

9. (2) 10. (2) 11. (2) 12. (2) 13. (1) 14. (2) 15. (2) 16. (3)

17. (2) 18. (2) 19. (1) 20. (1) 21. (1) 22. (3) 23. (1) 24. (4)

25. (1) 26. (3) 27. (3) 28. (2) 29. (4) 30. (4) 31. (1) 32. (3)

33. (1) 34. (2) 35. (2) 36. (3) 37. (3) 38. (1) 39. (1) 40. (2)

41. (3) 42. (3) 43. (4) 44. (2) 45. (1) 46. (2) 47. (4) 48. (1)

49. (2) 50. (1)


1. (2) 2. (4) 3. (2) 4. (1) 5. (1) 6. (3)

7. (4) 8. (3) 9. (1) 10. (2) 11. (1) 12. (4)

13. (3) 14. (4) 15. (1) 16. (2) 17. (2) 18. (1)

19. (4) 20. (4) 21. (4) 22. (3) 23. (1) 24. (4)

25. (2) 26. (3)

27. (3) 28. (4) 29. (1) 30. (3)

31. (3) 32. (4) 33. (4) 34. (4) 35. (4) 36. (3)

37. (4) 38. (1)


1. (3) 2. (4) 3. (3)

4. (3) 5. (1) 6. (3)

7. (1)

8. (1)

9. (2)

10. (3)

11. (3)

12. (4)

13. (4)

14. (4)

15. (1)

PREVIOUS YEAR QUESTIONS(HOME WORK)

1. (4) 2. (3) 3. (2) 4. (1) 5. (2) 6. (1) 7. (3) 8. (3) 9. (3) 10. (4) 11. (4) 12. (4) 13. (2) 14. (2) 15. (4) 16. (4) 17. (1) 18. (3) 19. (2) 20. (3) 21. (4)

22. (3) 23. (4) 24. (3) 25. (1) 26. (2) 27. (3) 28. (3) 29. (4) 30. (2) 31. (4) 32. (2) 33. (4) 34. (4) 35. (1) 36. (3) 37. (4) 38. (3) 39. (2) 40. (1) 41. (2)

42. (1)

43. (4) 44. (4) 45. (3) 46. (4) 47. (4) 48. (2) 49. (1) 50. (4) 51. (3) 52. (1) 53. (1) 54. (2) 55. (1) 56. (4) 57. (1) 58. (2) 59. (4) 60. (3) 61. (2) 62. (3) 63. (2)

64. (2) 65. (2) 66. (3) 67. (4) 68. (4) 69. (1) 70. (2) 71. (2) 72. (1) 73. (1) 74. (4) 75. (2) 76. (1) 77. (3) 78. (2) 79. (1) 80. (3)

81. (4) 82. (1) 83. (3) 84. (2)

85. (2) 86. (4) 87. (2) 88. (3) 89. (1) 90. (3) 91. (1) 92. (4) 93. (2) 94. (2) 95. (1) 96. (2) 97. (2) 98. (1) 99. (1) 100. (3) 101. (4) 102. (3) 103. (3) 104. (2) 105. (2)

106. (3) 107. (2) 108. (4) 109. (2) 110. (4) 111. (3) 112. (1) 113. (3) 114. (1) 115. (3) 116. (1) 117. (1) 118. (4) 119. (3) 120. (3) 121. (4) 122. (4) 123. (2) 124. (2) 125. (4) 126. (2)

127. (3) 128. (2) 129. (4) 130. (1) 131. (2) 132. (4) 133. (1) 134. (4) 135. (3) 136. (2) 137. (1) 138. (3)

139. (1)

140. (3)

141. (1)

142. (1)

143. (2)

144. (1)

145. (3)

146. (2)

————

INDEX

Topic Name Page No


Exercise 154-170

Level–I 154-156

Level–II 157-160



Answer Key 171-171

This chapter includes:

Introduction

How Many Species are there on Earth and How Many in India?

Biodiversity

Patterns of Biodiversity

Loss of Biodiversity

Biodiversity Conservation

How do we Conserve Biodiversity?

Biosphere Reserves

International and National Efforts to Conserve Biodiversity

Biosphere Reserves of India

Important National Parks and Sanctuaries of India

BIODIVERSITY AND CONSERVATION

Biodiversity and Conservation Rg.-Bot. XII-19-21


BIODIVERSITY

The term biodiversity refers to the totality of genes, species, and ecosystems of a region.

Biodiversity loss is now one of the world's most pressing crisis. The primary reason for the concern is the realization that biological diversity is being lost even before its size is known.

According to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million.

The common man would find it hard to believe that there are more than 20,000 species of ants, 3,00,000 species of beetles, 28,000 species of fishes and nearly 20,000 species of orchids.

The predicted number of total species averages at 1.7 million. About 61 per cent of the known species are insects. Only 4650 species of mammals are known to science. A large number of plant species (2,70,000) and vertebrates(53239) are known. Coral reefs and tropical forests are major regions expected to have a large number of species still unknown to man.

How Many Species are there on Earth and How Many in India? According to the IUCN (2004), the total number of plant and animal species

described so far is slightly more than 1.5 million, but we have no clear idea of how many species are yet to be discovered and described. Estimates vary widely and many of them are only educated guesses.

For many taxonomic groups, species inventories are more complete in temperate than in tropical countries. Considering that an overwhelmingly large proportion of the species waiting to be discovered are in the tropics, biologists make a statistical comparison of the temperate-tropical species richness of an exhaustively studied group of insects and extrapolate this ratio to other groups of animals and plants to come up with a gross estimate of the total number of species on earth.

Some extreme estimates range from 20 to 50 million, but a more conservative and scientifically sound estimate made by Robert May places the global species diversity at about 7 million.

More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total.

Among animals, insects are the most species-rich taxonomic group, making up more than 70 per cent of the total. That means, out of every 10 animals on this planet, 7 are insects.

The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals

These estimates do not give any figures for prokaryotes. Biologists are not sure about how many prokaryotic species there might be. The problem is that conventional taxonomic methods are not suitable for identifying microbial species and many species are simply not culturable under

BIODIVERSITY AND CONSERVATION



laboratory conditions. If we accept biochemical or molecular criteria for delineating species for this group, then their diversity alone might run into millions.

Although India has only 2.4 per cent of the world’s land area, its share of the global species diversity is an impressive 8.1 per cent. That is what makes our country one of the 12 mega diversity countries of the world. Nearly 45,000 species of plants and twice as many of animals have been recorded from India.

If we accept May’s global estimates, only 22 per cent of the total species have been recorded so far. Applying this proportion to India’s diversity figures, we estimate that there are probably more than 1,00,000 plant species and more than 3,00, 000 animal species yet to be discovered and described.

Representing global biodiversity: proportionate number of species of major taxa of plants, invertebrates and vertebrates

Table : Approximate numbers of species which have been

described and identified from all over the world.

Group Numbers of species

Higher Plants 2,70,000

Algae 40,000

Fungi 72,000

Bacteria (including cyanobacteria) 4,000

Viruses 1,550

Mammals 4,650

Birds 9,700

Reptiles 7,150

Fish 28,000

Amphibians 4,7 80

Insects 10,25,000

Crustaceans 43,000

Molluscs 70,000

Nematodes and worms 25,000

Protozoa 40,000

Ants 20,000

Beetles 3,00,000

Orchids 20,000

Others 1,10,000

Table : The number of species of different taxonomic groups, described from India.



BIODIVERSITY In our biosphere immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organisation ranging from macromolecules within cells to biomes. Biodiversity is the term popularized by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation.

Levels of Biodiversity

Biological diversity includes three hierarchical levels :

(i) Genetic diversity

(ii) Species diversity

(iii) Community and ecosystem diversity.

(i) Genetic diversity : Genetic diversity refers to the variation of genes within species; the

differences could be in alleles, in entire genes (the traits determining particular characteristics) or

in chromosomal structures. The genetic diversity enables a population to adapt to its environment

and to respond to natural selection.

The amount of genetic variation is the basis of speciation (evolution of new species). It has a key

role in the maintenance of diversity at species and community levels. Genetic diversity of a

community will be greater if there are many species.

A single species might show high diversity at the genetic level over its distributional range. The genetic variation shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces. India has more than 50,000 genetically different strains of rice, and



1000 varieties of mango.

Lower genetic diversity within a species or variety may be useful for uniformity in yield and higher yield but is prone to mass destruction by pests/pathogens.

(ii) Species diversity: Species are distinct units of diversity. Species diversity refers to the variety

of species within a region. Simplest measure of species diversity is Species richness, i.e., the

number of species per unit area. The number of species increases with the area of the site.

Another measure of diversity is species evenness which is number of individuals of different

species.

In nature, both the number and kind of species, as well as the number of individuals per species

vary, leading to greater diversity. For example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats in India.

(iii) Ecosystem diversity: Diversity at the level of community and ecosystem has three perspectives.

Alpha diversity (within- community diversity), Beta diversity (between-community diversity).

Diversity of the habitats over the total landscape or geographical area is called Gamma

diversity.

Ecosystem diversity describes the number of niches, trophic levels and various ecological

processes that sustain energy flow.

At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

It has taken millions of years of evolution, to accumulate this rich diversity in nature, but we could lose all that wealth in less than two centuries if the present rates of species losses continue. Biodiversity and its conservation are now vital environmental issues of international concern as more and more people around the world begin to realize the critical importance of biodiversity for our survival and well- being on this planet.

Biogeographical regions of India are:

1. Trans Himalayas

2. Himalayas

3. Desert

4. Semi arid

5. Western Ghats

6. Deccan Peninsula

7. Gangetic Plain

8. Coasts

9. North East

10. Islands

Deccan Peninsula has the most extensive coverage of the Indian landmass about 42 percent.

About 33% flowering plants recorded in India are endemic to our country.

10% mammalian fauna are endemic to India. The most biodiversity rich regions are Western Ghats (area 4%) and North East (area

5.2%).



Patterns of Biodiversity

(i) Latitudinal and altitudinal gradients : The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution. For many group of animals or plants, there are interesting patterns in diversity, the most well- known being the latitudinal gradient in diversity.

In general, species diversity decreases as we move away from the equator towards the poles. With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas. Columbia located near the equator has nearly 1,400 species of birds while New York at 41° N has 105 species and Greenland at 71° N only 56 species. India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.

A forest in a tropical region like Equador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA.

The largely tropical Amazonian rain forest in South America has the greatest biodiversity on earth- it is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and of more than 1,25,000 invertebrates. Scientists estimate that in these rain forests there might be at least two million insect species waiting to be discovered and named.

A decrease in species diversity occurs as we ascend a high mountain due to drop in temperature and greater seasonal variability.

Why tropical region has more diversity

Ecologists and evolutionary biologists have proposed various hypotheses; some important ones are

(1) Speciation is generally a function of time, unlike temperate regions subjected to frequent glaciations in the past, tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.

(2) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and lead to a greater species diversity.

(3) There is more solar energy available in the tropics, which contributes to higher productivity; this in turn might contribute indirectly to greater diversity.

(ii) Species-Area relationships : During his pioneering and extensive explorations in the wilderness of South American jungles, the great German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit. In fact, the relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola Figure.

On a logarithmic scale, the relationship is a straight line described by the



equation log S = log C + Z log A where S= Species richness A= Area Z = slope of the line (regression coefficient) C = Y-intercept

Showing species area relationship.

Note that on log scale the relationship becomes linear Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2,

regardless of the taxonomic group or the region (whether it is the plants in Britain, birds in California or molluscs in New York state, the slopes of the regression line are amazingly similar).

But, if you analyse the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2). For example, for frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents, the slope is found to be 1.15.

The importance of Species Diversity to the Ecosystem For many decades, ecologists believed that communities with more species,

generally, tend to be more stable than those with less species. What exactly is stability for a biological community? A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species.

David Tilman’s long-term ecosystem experiments using outdoor plots provide some tentative answers. Tilman found that plots with more species showed less year-to-year variation in total biomass. He also showed that in his experiments, increased diversity contributed to higher productivity. Rich biodiversity is not only essential for ecosystem health but imperative for the very survival of the human race on this planet.

At a time when we are losing species at an alarming pace, one might ask– Does it really matter to us if a few species become extinct? Would Western Ghats ecosystems be less functional if one of its tree frog species is lost forever? How is our quality of life affected if, say, instead of 20,000 we have only 15,000 species of ants on earth?



There are no direct answers to such näive questions but we can develop a proper perspective through an analogy (the ‘rivet popper hypothesis’) used by Stanford ecologist Paul Ehrlich. In an airplane (ecosystem) all parts are joined together using thousands of rivets (species). If every passenger travelling in it starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time. Furthermore, which rivet is removed may also be critical. Loss of rivets on the wings (key species that drive major ecosystem functions) is obviously a more serious threat to flight safety than loss of a few rivets on the seats or windows inside the plane.

Loss of Biodiversity The biological wealth of our planet has been declining rapidly and the

accusing finger is clearly pointing to human activities. The colonisation of tropical Pacific Islands by humans is said to have led to

the extinction of more than 2,000 species of native birds. The IUCN Red List (2004) documents the extinction of 784 species (including

338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years. Some examples of recent extinctions include the dodo (Mauritius), quagga

(Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three subspecies (Bali, Javan, Caspian) of tiger. The last twenty years alone have witnessed the disappearance of 27 species.

Careful analysis of records shows that extinctions across taxa are not random; some groups like amphibians appear to be more vulnerable to extinction. Adding to the grim scenario of extinctions is the fact that more than 15,500 species world-wide are facing the threat of extinction. Presently, 12 per cent of all bird species, 23 per cent of all mammal species, 32 per cent of all amphibian species and 31per cent of all gymnosperm species in the world face the threat of extinction.

From a study of the history of life on earth through fossil records, it is learned that large-scale loss of species like the one we are currently witnessing have also happened earlier, even before humans appeared on the scene. During the long period (> 3 billion years) since the origin and diversification of life on earth there were five episodes of mass extinction of species.

‘Sixth Extinction’ presently in progress different from the previous episodes? The difference is in the rates; the current species extinction rates are estimated to be 100 to 1,000 times faster than in the pre-human times and our activities are responsible for the faster rates. Ecologists warn that if the present trends continue, nearly half of all the species on earth might be wiped out within the next 100 years.

In general, loss of biodiversity in a region may lead to (1) decline in plant production, (2) lowered resistance to environmental perturbations such as drought and (3) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles.

Causes of biodiversity losses: The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes (‘ The Evil Quartet ’).



(i) Habitat loss and fragmentation: This is the most important cause driving animals and plants to extinction. The most dramatic examples of habitat loss come from tropical rain forests. Once covering more than 14 per cent of the earth’s land surface, these rain forests now cover no more than 6 per cent. They are being destroyed fast. The Amazon rain forest (it is so huge that it is called the ‘lungs of the

planet’) harbouring probably millions of species is being cut and cleared for cultivating soya beans or for conversion to grasslands for raising beef cattle. Besides total loss, the degradation of many habitats by pollution also threatens the survival of many species. When large habitats are broken up into small fragments due to various human activities, mammals and birds requiring large territories and certain animals with migratory habits are badly affected, leading to population declines.

(ii) Over-exploitation: Humans have always depended on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to over-exploitation of natural resources. Many species extinctions in the last 500 years (Steller’s sea cow, passenger pigeon) were due to overexploitation by humans. Presently many marine fish populations around the world are over harvested, endangering the continued existence of some commercially important species.

(iii) Alien species invasions: When alien species are introduced unintentionally or deliberately for whatever purpose, some of them turn invasive, and cause decline or extinction of indigenous species. The Nile perch introduced into Lake Victoria in east Africa led eventually

to the extinction of an ecologically unique assemblage of more than 200 species of Cichlid fish in the lake.

Environmental damage has been caused and threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eicchornia). The recent illegal introduction of the African catfish Clarias gariepinus for aquaculture purposes is posing a threat to the indigenous catfishes in our rivers.

(iv) Co-extinctions: When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct. When a host fish species becomes extinct, its unique assemblage of

parasites also meets the same fate. Another example is the case of a coevolved plant-pollinator mutualism as

in Yucca and Pronuba moth where extinction of one will invariably lead to the extinction of the other.

BIODIVERSITY CONSERVATION Why Should We Conserve Biodiversity? There are many reasons, some obvious and others not so obvious, but all

equally important. They can be grouped into three categories: narrowly utilitarian, broadly utilitarian, and ethical. (i) The narrowly utilitarian arguments for conserving biodiversity are

obvious; humans derive countless direct economic benefits from nature food (cereals, pulses, fruits), firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and products of medicinal importance.



More than 25 per cent of the drugs currently sold in the market worldwide are derived from plants and 25,000 species of plants contribute to the traditional medicines used by native people around the world. Nobody knows how many more medicinally useful plants there are in tropical rain forests waiting to be explored.

With increasing resources put into ‘bioprospecting’ (exploring molecular, genetic and species-level diversity for products of economic importance), nations endowed with rich biodiversity can expect to reap enormous benefits.

(ii) The broadly utilitarian argument says that biodiversity plays a major role in many ecosystem services that nature provides.

The fast dwindling Amazon forest is estimated to produce, through photosynthesis, 20 per cent of the total oxygen in the earth’s atmosphere.

Pollination (without which plants cannot give us fruits or seeds) is another service, ecosystems provide through pollinators – bees, bumblebees, birds and bats.

There are other intangible benefits – that we derive from nature–the aesthetic pleasures of walking through thick woods, watching spring flowers in full bloom or waking up to a bulbul’s song in the morning.

(iii) The ethical argument for conserving biodiversity relates to what we

owe to millions of plant, animal and microbe species with whom we share this planet. Philosophically or spiritually, we need to realise that every species has an intrinsic value, even if it may not be of current or any economic value to us. We have a moral duty to care for their well-being and pass on our biological legacy in good order to future generations.

How do we conserve Biodiversity? When we conserve and protect the whole ecosystem, its biodiversity at all levels is protected; we save the entire forest to save the tiger. This approach is called in situ

(on site) conservation. However, when there are situations where an animal or plant is endangered or threatened and needs urgent measures to save it from extinction, ex situ (off site) conservation is the desirable approach.

In situ CONSERVATION

Faced with the conflict between development and conservation, many nations find it unrealistic and economically not feasible to conserve all their biological wealth. Invariably, the number of species waiting to be saved from extinction far exceeds the conservation resources available.

On a global basis, this problem has been addressed by eminent conservationists. They identified for maximum protection certain ‘biodiversity hotspots’ regions with very high levels of species richness and high degree of endemism (that is, species confined to that region and not found anywhere else). Initially 25 biodiversity hotspots were identified but subsequently nine more have been added to the list, bringing the total number of biodiversity hotspots in the world to 34.



These hotspots are also regions of accelerated habitat loss. Three of these hotspots – Western Ghats and Sri Lanka, Indo-Burma and Himalaya – cover our country’s exceptionally high biodiversity regions. Although all the biodiversity hotspots put together cover less than 2 percent of the earth’s land area, the number of species they collectively harbour is extremely high and strict protection of these hotspots could reduce the ongoing mass extinctions by almost 30 per cent.

In India, ecologically unique and biodiversity-rich regions are legally protected as biosphere reserves, national parks and sanctuaries. India now has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries.

India has also a history of religious and cultural traditions that emphasised protection of nature. In many cultures, tracts of forest were set aside, and all the trees and wildlife within were venerated and given total protection. Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya, Aravalli Hills of Rajasthan, Western Ghat regions of Karnataka and Maharashtra and the Sarguja, Chanda and Bastar areas of Madhya Pradesh.

In Meghalaya, the sacred groves are the last refuges for a large number of rare and threatened plants.

Ex situ CONSERVATION In this approach, threatened animals and plants are taken out from their

natural habitat and placed in special setting where they can be protected and given special care.

Zoological parks, botanical gardens and wildlife safari parks serve this purpose. There are many animals that have become extinct in the wild but continue to be maintained in zoological parks.

In recent years ex situ conservation has advanced beyond keeping threatened species in enclosures. Now gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques, eggs can be fertilised in vitro, and plants can be propagated using tissue culture methods. Seeds of different genetic strains of commercially important plants can be kept for long periods in seed banks.

Biodiversity knows no political boundaries and its conservation is therefore a collective responsibility of all nations. The historic Convention on Biological Diversity (‘The Earth Summit’) held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilisation of its benefits.

In a follow-up, the World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.

Biosphere Reserves They are large tracts of protected land with multiple use preserving the

genetic diversity of representative ecosystem by protecting wild life, traditional life styles of the tribals and varied plant and animal genetic resources.



They have been set up under MAB program of UNESCO. A total of 408 biosphere reserves are to be set up in 94 countries.

Fig.: The zonation in a terrestiral Biosphere Reserve

Each biosphere reserve has (i) Core Zone, No human activity is permitted (ii) Buffer Zone. Limited human activity is allowed. (iii) Manipulation Zone. All types of human activities which do not disturb

ecology are allowed. International and national efforts to conserve Biodiversity Earth summit (1992) at Rio de Janeiro, Brazil, promoted Convention on Biological diversity which was signed by 152 nations. Agenda 21 is a blue print for encouraging sustainable development of diversity through social, economic and environmental measures in the 21st Century. It was formulated during the Earth summit. NGOs like Green Peace provide international support for conservation. WWF or World Wide Fund and World Conservation Union are organizations working for conservation of biodiversity. Convention in International Trade in Endangered Species (CITES) has helped to restrict poaching and loss of rare species. In India in situ conservation is undertaken by ministry of environment and forest. Major ex situ conservation of biodiversity is being managed by National Bureau of Plant, Animal and Fish Genetic Resources.

Silviculture is the management of forests or woodlands for production of timber and wood products. Chipko movement started by Sundar Lal Bahuguna and Appiko movement of Karnataka both resisted deforestation. Red Data Book contains a record of animals and plants known to be in danger and is maintained by IUCN. IUCN is International Union of Conservation of Nature and Natural Resources with its headquarters at Morges, Switzerland. It is now called World Conservation Union (WCU). The red list maintained in the red data book has 8 categories of species:

1. Extinct: e.g. Dodo

2. Extinct in Wild



3. Critically endangered: In India (18 animals and 44 plants) e.g. Pygmy Hog, Podophyllum etc

4. Endangered: (In India 54 animals and 113 plants) e.g. Red Panda, Blue Whale, Lemur Idri idri of Madagascar, Asiatic Wild Ass of Kutch, Lion Tailed Macaque etc.

5. Vulnerable: (In India 143 animals and 87 plants) e.g. Black Buck.

6. Lower Risk: (In India 109 animals and 73 plants)

7. Data deficiency

8. Not evaluated

Other than the above categories the list also includes

1. Rare species. E.g. Clouded Leopard of Himalayas, Hawaiian Monk Seal, Great Indian Bustard of Gujarat and Rajasthan etc.

2. Indeterminate species. E.g. Three Banded Armadillo of Brazil, Short Eared Rabbit of Sumatra, Mexican Prairie Dog etc.

Biosphere Reserves of India

Now India has 18 biosphere reserves which are as follows:

S.No. Name Location State Type Key Fauna

1. Great Rann of

Kutch

Part

of Kutch, Rajkot, Surendranagar and

Patan Districts

Gujarat Desert

Indian Wild

Ass

2. Gulf of

Mannar

Indian part of Gulf of Mannar

extending from Rameswaram island in

the North to Kanyakumari in the

South of Tamil Nadu and Sri Lanka

Tamil Nadu Coasts

Dugong or Sea

Cow

3. Sundarbans

Part of delta

of Ganges and Barahamaputra river

system

West Bengal

Gangetic

Delta

Royal Bengal

Tiger

4. Cold Desert

Pin Valley National Park and

surroundings; Chandratal and Sarchu

and Kibber Wildlife Sancturary

Himachal

Pradesh

WesternHi

malayas Snow Leopard

5. Nandadevi

Parts of Chamoli District, Pithoragarh

District & Bageshwar District Uttarakhand

WesternHi

malayas

6.

Nilgiri

Biosphere

Reserve

Part

of Waynad, Nagarhole, Bandipur and

Mudumalai, Nilambur,Silent

Valley and Siruvani Hills

Tamil Nadu,

Kerala and

Karnataka

Western

Ghats

Nilgiri

Tahr, Lion-

tailed macaque

7. Dihang-

Dibang

Part of Siang and Dibang Valley Arunachal

Pradesh

Eastern

Himalaya

8.

Pachmarhi

Biosphere

Reserve

Parts of Betul District, Hoshangabad

District and Chhindwara District

Madhya

Pradesh

Semi-Arid

Giant

Squirrel, Flying

Squirrel

9. Seshachalam

Hills

Seshachalam Hill Ranges covering

parts of Chittoor and Kadapa districts

Andhra

Pradesh

Eastern

Ghats

10. Simlipal Part of Mayurbhanj district Odisha Deccan Gaur, Royal



S.No. Name Location State Type Key Fauna

Peninsula Bengal

Tiger, Wild

elephant

11. Achanakamar

-Amarkantak

Part of Annupur, Dindori and Bilaspur

districts

Madhya

Pradesh,

Chhattisgarh

Maikala

Range

12. Manas

Part of Kokrajhar, Bongaigaon,

Barpeta, Nalbari, Kamrup and

Darrang Districts

Assam

East

Himalayas

Golden

Langur, Red

Panda

13. Khangchendz

onga

Parts of Kanchanjunga Hills Sikkim

East

Himalayas

Snow

Leopard, Red

Panda

14.

Agasthyamal

ai Biosphere

Reserve

Neyyar, Peppara and Shenduruny

Wildlife Sanctuary and their adjoining

areas

Kerala, Tamil

Nadu

Western

ghats

Nilgiri

Tahr, Elephants

15.

Great Nicobar

Biosphere

Reserve

Southern most islands of Andaman

and Nicobar Islands

Andaman and

Nicobar

Islands

Islands

Saltwater

Crocodile

16. Nokrek Part of Garo Hills Meghalaya

East

Himalayas

Red Panda

17. Dibru-

Saikhowa

Part of Dibrugarh and Tinsukia

districts Assam

East

Himalayas

Golden Langur

18. Panna Part of Panna and Chattarpur Districts Madhya

Pradesh

catchment

area of the

Ken River

tiger, chital,

chinkara,

sambhar and

sloth bear

Important National Parks and Sanctuaries of India

Andaman and Nicobar Islands

1. Barren Island Sanctuary (Bay of Bengal)

2. Mount Harriet National Park

3. North Reef Island Sanctuary (Bay of Bengal)

4. Saddle Peak National Park (Bay of Bengal)

5. South Button Island National Park (Andaman)

Andhra Pradesh

1. Coringa Sanctuary (East Godavari)

2. Kolleru Sanctuary (West Godavari)

3. Nagarjunasagar Srisailam/Ikshwaka Sanctuary (Guntur, Kurnool)

4. Neelapathu Sanctuary (Nellore)

5. Pakhal Sanctuary (Warangal)

Arunachal Pradesh



1. Itanagar Sanctuary

2. Namdapha National Park

3. Pakhui Sanctuary

Assam

1. Kaziranga National Park (Sibsagar and Nowgong)

2. Manas National Park (Barpeta)

3. Namdapha National Park

Bihar

1. Hazaribagh Sanctuary (Hazaribagh)

2. Palamau Sanctuary/National Park (Dalton Ganj), also part in Orissa

3. Rajgir Sanctuary

Chandigarh

1. Sukhana Lake Sanctuary

Delhi

1. Indira Priyadarshini Sanctuary

Goa

1. Bhagwan Mahavir Sanctuary/National Park

Gujarat

1. Gir National Park (Gir, Junagarh)

2. Marine National Park (Jamnagar)

3. Nalsorovar Sanctuary (Ahmedabad)

Haryana

1. Bhindawas Sanctuary

2. Sultanpur (Lake) Sanctuary (Gurgoan)

Himachal Pradesh

1. Great Himalayan National Park

2. Manali Sanctuary

3. Pin Valley National Park

Jammu & Kashmir

1. Dachigam Sanctuary/National Park (Srinagar)

2. Gulmarg Sanctuary

3. Karakoram Sanctuary

4. Kishtwar National Park (Srinagar)

5. Salim Ali National Park

6. Surinsar-Mansar Sanctuary

Karnataka

1. Bandipur National Park (Mysore)

2. Cauvery Sanctuary

3. Gataprabha Sanctuary (Belgaun)

4. Ranganathitti (Bird) Sanctuary (Mysore)



Kerala

1. Eravikulum National Park (Idukki)

2. Idukki Sanctuary (Idukki)

3. Neyyar Sanctuary

4. Periyar National Park (Idukki)

5. Silent Valley National Park (Palaghat)

Madhya Pradesh

1. Bandhavgarh National Park (Shahdol)

2. Fossil National Park

3. Gandhi Sagar Sanctuary

4. Kanha National Park (Mandla and Balaghat)

5. Karera Sanctuary/Great Indian Bustard Sanctuary

6. National Chambal Sanctuary

7. Panna National Park (Panna)

8. Pench National Park

9. Sanjay National Park (Sidhi and Surguja)

10. Satpura National Park (Hoshangabad)

Van Vihar National Park (Bhopal)

Maharashtra

1. Chandoli Sanctuary

2. Great Indian Bustard Sanctuary

3. Koyna Sanctuary

4. Sanjay Gandhi National Park (Mumbai)

Manipur

1. Siroy National Park (Manipur East)

Meghalaya

1. Balphakram National Park

2. Nokrek National Park

Mizoram

1. Dampa Sanctuary

Orissa

1. Chilka Lake Bird Sanctuary (Balagoan)

2. Palamau National Park (also in Bihar)

Punjab

1. Abohar Sanctuary

2. Bir Motibagh Wild Life Sanctuary

3. Debrigarh Sanctuary



Rajasthan

1. Desert National Park (Jaiselmer and Barmer)

2. Jawahar Sagar Sanctuary

3. Keoladeo/Ghana Bird Sanctuary National Park

4. Mount Abu Sanctuary (Bharatpur)

5. National Gharial Sanctuary

6. Ramgarh Sanctuary

7. Ranthambore National Park (Savai Madhopur)

8. Sariska Sanctuary/National Park (Alwar)

Tamil Nadu

1. Anamalai Sanctuary (Coimbatore)

2. Guindy National Park (Madras)

3. Marine National Park (Gulf of Mannar)

4. Mudumalai Wild Life Sanctuary (Nilgiri)

5. Pulicat (Lake) Sanctuary

Uttaranchal

1. Corbett National Park (Nainital)-First to be established

2. Nanda Devi National Park (Chamoli)

3. Valley of Flowers National Park (Chamoli)

Uttar Pradesh

1. Chandraprabha Sanctuary (Varanasi)

2. Dudhwa National Park (Lakhimpur Kheri)

3. Hastinapur Sanctuary

West Bengal

1. Sunderbans Tiger Reserve/National Park (24-Parganas)

————




1. What is Biodiversity? (1) Species in a region (2) Genes & species in a region (3) Genetic, species & ecological diversity in a region (4) Genes and species in an ecosystem

2. Threats to biodiversity comes from (1) Habitat loss (2) Over exploitation (3) Shifting Cultivation (4) All

3. Which species is most likely to be positively selected by natural selection? (1) One with a large gene pool (2) One with a medium gene pool (3) One with a small gene pool (4) No correlation exists between gene pool and natural selection

4. Fill up the blanks- Initially _A_ biodiversity hotspots were identified but subsequently nine more have

been added to the list, bringing the total number of biodiversity hotspots in the world to _B_. These hotspots are also regions of accelerated habitat loss. Three of these hotspots - Western Ghats and Sri Lanka, lndo-Burma and Himalaya - cover

our country's exceptionally high biodiversity regions. Although all the biodiversity hotspots put together cover less than _C_ % of the earth‟s land area, the number of species they collectively harbour is extremely high and strict protection of these hotspots could reduce the ongoing mass extinctions by almost _D_ %.

(1) A-25, B-34, C-2, D-30 (2) A-25,B-34,C-4,D-30 (3) A-25, B-34, C-10, D-30 (4) A-15, B-24, C-4, D-30

5. The diversity of organisms sharing the same habitat or community is termed as …. (1) Alpha (2) Beta (3) Gamma (4) Delta

6. Which one of the following are two hotspots of biodiversity in India? (1) Western ghats & North Eastern Himalayas (2) Deccan and Western Ghats (3) Himalayan and Deccan Plateau (4) Western Ghats and Gangetic Plains

7. What is the affect of species diversity, as one moves from high to low altitudes. (1) Increases (2) Decreases (3) First increases then decreases (4) First decreases then increases

8. Which of the following is not an example of in-situ conservation? (1) Biosphere Reserves (2) National Parks (3) Wildlife Sanctuaries (4) Zoos and botanical gardens

9. The numbers of National Parks, Biosphere and Wildlife sanctuaries of India were: (1) 90,14,448 (2) 158, 62, 10 (3) 58, 412, 10 (4) 96, 412, 10



10. Which of the following was the first National Park of India? (1) Corbett (2) Nanda Devi (3) Kaziranga (4) Jaldapara

11. ln which part of biosphere reserves human settlement is permissible? (1) Buffer Zone (2) Transition Zone (3) Core Zone (4) Settlement not allowed in any zone

12. As estimated by Robert May, what is the total number of species present on earth? (1) 3 million (2) 5 million (3) 7 million (4) 9 million

13. Species diversity ……….as we move away from the equator towards the poles, (1) Increases (2) Decreases (3) First increases then decreases (4) First decreases then increases

14. When was Biodiversity Act of India passed by Parliament? (1) 1992 (2) 1996 (3) 2000 (4) 2002

15. What are the total number of hot spots present in the world? (1) 25 (2) 29 (3) 34 (4) 39

16. Where was the World Summit on Sustainable Development held? (1) South Africa (2) U.S.A. (3) South Korea (4) U.K.

17. Which of the following phyla has largest number of species? (1) Arthropoda (2) Echinodermata (3) Cephalochordata (4) Annelida

18. What is the approximate percentage of the earth covered by terrestrial hot spots? (1) 1.5% (less than 2%) (2) 2.5% (3) 3.5% (4) 4.5%

19. In which year Convention on Biodiversity came into force? (1) 1992 (2) 1993 (3) 1994 (4) 1995 20. Which is not an objective of Convention on Biodiversity? (1) Conservation of Biodiversity (2) Sustainable use of Biodiversity (3) Fair and equitable sharing of profits arising out of genetic resources (4) Selective hunting of dangerous and threatening species 21. Sacred groves in India are found in (1) Jaintia hills of Karnataka (2) Western Ghat regions of Tamil Nadu (3) Aravalli hills of Meghalaya (4) Bastar areas of Madhya Pradesh

22. The term “The Evil Quartet” is related with (1) Four major causes of forest loss (2) Four major causes of population explosion (3) Four major causes of air pollution (4) Four major causes of biodiversity losses



23. The ………encourages the division of protected areas into zones with different purposes and levels of human impact.

(1) Man and Biosphere Program (MAB) (2) Biosphere Reserve (3) Chipko Andolan Movement (4) IUCN world conservation strategy

24. The narrowly utilitarian arguments for conserving include which of the following from the given list?

(i) Industrial products like dyes, lubricants. (ii) Ecosystem services like photosynthesis. (iii) Pollinators layer of bees, birds and bats. (iv) Firewood, fibre and construction material. (v) The aesthetic pleasure of walking through thick. (vi) Products of medicinal importance. (vii) Watching spring flowers in full bloom. (viii) Our moral duty to care for the well-being of each species. (1) (i), (ii), (v) and (vii) (2) (ii), (iii), (v) and (vii) (3) (i), (iv) and (vi) (4) (iii), (v), (vii) and (viii)

25. Which of the following countries has the most deforestation today? (1) Brazil (2) United States (3) Japan (4) none of the above

26. What is sustainable use? (1) The study of methods to help protect biodiversity.

(2) Protected strips of land that allow organisms to migrate from one wilderness area to another

(3) A law that makes it illegal to do harm to species that are listed as endangered or threatened

(4) The ability to use natural resources in a way that helps people and protects the ecosystem.

27. Which of these statements is true? (1) Biodiversity tends to increase as you get closer to the equator (2) Tropical regions of Earth contain very few of the world‟s land species.

(3) Coral reefs tend to be less biologically diverse than temperate deciduous forests. (4) Cold climates have greater amounts of biodiversity than warm climates.

28. Why are conservationists calling for immediate, and often expensive, action on behalf of endangered species and habitats?

(1) Biodiversity is beneficial to humans. (2) Man has brought on climate change. (3) Extinction is an unnatural process. (4) lt would be more costly, financially, if we did not act.

29. Which of the following is NOT a benefit that humans receive from a biologically diverse world?

(1) Source of geothermal energy (2) Source of water (3) Source of economic gains (4) Source of food

30. When the last member of a particular species dies, the species is said to be ….. (1) Isolated (2) Endangered (3) Diversified (4) Extinct




31. A keystone species is one that (1) Has a higher likelihood of extinction than a non keystone species (2) Exerts a strong influence on an ecosystem. (3) Causes other species to become extinct. (4) Has a weak influence on an ecosystem.

32. Most large whale species have been driven to the brink of extinction. Which of the following is the most accepted explanation for this situation?

(1) Overexploitation (2) Habitat loss (3) Pollution (4) Competition from introduced species

33. Historically, island species have tended to become extinct faster than species living on a mainland. Which of the following reasons cannot be used to explain this phenomenon?

(1) Island species have often evolved in the absence of predators and have no natural avoidance strategies.

(2) Humans have introduced diseases and competitors to islands, which negatively impacts island populations.

(3) Island populations are usually smaller than mainland populations. (4) Island populations are usually less fit than mainland populations.

34. An endemic species is (1) one found in many different geographic areas. (2) one found naturally in just one geographic area. (3) one found only on islands. (4) one that has been introduced to a new geographic area

35. Conservation hotspots are best described as (1) Areas with large numbers of endemic species and species richness. (2) Areas where people are particularly active supporters of biological diversity. (3) Islands that are experiencing high rates of extinction. (4) Areas where native species ate being replaced with introduced species.

36. The reasons behind conserving biodiversity can be group into categories which include

A. Narrowly utilitarian B. Broadly utilitarian C. Ethical- utilitarian D. No utilitarian (1) A, B (2) A, B, C (3) B, C (4) D 37. ln situ strategies include A. Biosphere reserve B. National park C. Wildlife sanctuaries D. sacred forests/ lakes (1) A, B (2) A, B, C (3) B, C, D (4) A, B, C, D 38. Ex situ strategies include A, Botanical garden B. Zoos C. Seed/ Pollen banks D. Gene bank and tissue culture (1) A, B (2) A, B, C (3) B, C, D (4) A, B, C, D 39. A. More than 70 percent of all the species recorded are animals.



B. Out of every 10 animals on this planet, 7 are insects. C. The number of fungi species in the world is more than the combined total of the

species of fishes, amphibians reptiles and mammals. D. Number of fishes is very less than that of mammals. (1) All correct (2) All incorrect (3) A, B and C are correct (4) Only D is correct

40. Sacred groves are found in A. Khasi and Jaintia Hills in Meghalaya B. Aravalli Hills of Rajasthan

C. Western ghat regions of Karnataka and Maharashtra and Sarguja, Chanda and Bastar areas of Madhya Pradesh

D. None (1) A (2) A, B, C (3) B, C, D (4) D

41. According to the concept of species area relations (1) The number of species in an area increases with the size of the area (2) Larger species require larger habitat areas than do smaller species. (3) Most species within any given area are endemic. (4) The larger the area, the greater the extinction rate.

42. A species-area relation is used by ecologists to (1) Determine the population density of a species in a certain habitat. (2) Examine how human populations are growing (3) Estimate the number of species extinctions resulting from habitat destruction (4) None 43. What effect, if any, would the extinction of a mutualistic pollinator have on the plant it

pollinates? (1) Decreased growth of plant (2) Decreased pollination (3) No effect because substitute pollinator is available. (4) The plant would not be pollinated and would face extinction. 44. Which is / are correct about Amazon rain forest? A. It is called Lungs of the planet. B. lt is being cut and cleared for cultivating soya beans or for conversion to

grasslands for raising beef cattle. C. The largely tropical rain forest in South America has highest biodiversity on

earth. D. It harbours probably millions of species. (1) A, B (2) A, B, C (3) B, C, D (4) A, B, C, D 45. Select the correct statement(s). A. India has more than 50,000 genetically different strains of rice B. India has 1000 varieties of mango C. The genetic variation in Rauwolfia vomitoria can be in terms of concentration

and potency of reserpine. D. The tropical rain forest initially covered 14% of the land surface of earth, but now

they cover only 6% of the land area (1) A, B (2) A, B, C (3) B, C, D (4) A, B, C, D



46. An exotic species that is introduced to a new area, spreads rapidly and eliminates native species is called

(1) An immigrant species (2) An invasive species (3) Destructive species (4) None

47. The exotic species which have been introduced in India (1) Lantana (2) Water Hyacinth (Eicchornia) (3) Parthenium (4) All

48. Which of the following fish is exotic species introduced in India for aquaculture (1) Dog fish (2) Shark (3) Catfish (4) Labeo

49. More than 25% of drugs are derived from plants. What benefits does this describe? (1) Ethical value (2) Aesthetic value (3) Direct economic value (4) Indirect economic value

50. Exploring molecular, genetic and species-level diversity for products of economic importance like medicines is called

(1) Bioremediation (2) Bio prospecting (3) Bioprocessing (4) Ecosystem services

51. Modern Ex situ conservation includes (1) Cryopreservation techniques (2) in vitro fertilisation (3) Plants can be propagated using tissue culture methods (4) All

52. Ex situ conservation is used for the conservation of- (1) All plants (2) All animals (3) threatened animals and plants (4) None

53. The impacts of loss of biodiversity include A. Decrease in plant production. B. Lowered resistance to environmental perturbation.

C. Increased variability in ecosystem processes like water use, pest/ disease cycle, plants productivity.

D. None (1) A, B (2) A, B, C (3) B, C (4) D

54. The characters of a stable community A. It shall not show too many variations in year to-year productivity. B. lt must be either resistance or resilient to seasonal disturbance. C. lt must be resistant to invasion by alien species. D. None (1) A, B (2) A, B, C (3) B, C (4) D

55. Biodiversity loss occurs due to A. Habitat loss and fragmentation B. Co-extinction C. Over-exploitation D. Alien species invasion. (1) A, B (2) A, B, C (3) B, C, D (4) A, B, C, D



56. Column I Column II I. Dodo (1) Rauwolfia II. Reserpine (2) Mauritius III. Botanical gardens (3) Khasi and Jaintia hills IV. Sacred forests (4) Ex-situ conservation

(1) I B, II A, III D, IV C (2) I D, II A, III B, IV C

(3) I A, II C, III B, IV D (4) I B, II A, III C, IV D 57. Column I Column II I. Nile Perch in Lake Victoria (1) Obvious reasons for biodiversity

conservation II. Narrowly utilitarian (2) Habitat destruction III. Main cause for biodiversity loss (3) High endemism IV. Hot spots (4) Alien species

(a) I B, II A, III D, IV C (2) I D, II A, III B, IV C

(3) I A, II C, III B, IV D (4) I B, II A, III C, IV D 58. Column I Column II I. Term Biodiversity (1) Edward Wilson II. In situ conservation (2) Co-extinction III. Plant pollination(mutualistic) (3) On-site conservation IV. Ex-situ conservation (4) Offsite conservation

(1) I B, II A, III D, IV C (2) I D, II A, III B, IV C

(3) I A, II C, III B, IV D (4) I B, II A, III C, IV D 59. ln recent years the number of species driven to extinction has increased dramatically.

Which of the following is not a reason for this? (1) Overexploitation (2) Habitat destruction (3) Introduction of predators (4) Natural predation 60. Why do species extinctions matter? (1) They don‟t matter unless the species is a human food source. (2) Many pharmaceutical products are derived from natural products, loss of species

could mean loss of therapeutic drugs (3) Soil erosion may increase if certain plants go extinct. (4) b and c











1. A : Forests are renewable resource. R : Conservation of forest has multifold benefits. 2. A : Coral reef is highly productive region. R : It shows maximum diversity of biota. 3. A : Biosphere reserves are in situ method of conservation. R : They ensure protection to wild life in their original habitat 4. A : Genetic diversity is a basis of speciation. R : Species richness is number of species per unit area. 5. A : Reptiles are more critically endangered than bird species. R : Conservation of biodiversity is practised only in hot spot areas. 6. A : Nile perch threatens the entire ecosystem of lake Victoria. R : Exotic species can be the reason for the extinction of the native species. 7. A : In situ conservation means conservation of organisms in their natural habitat. R : Zoo is an in situ conservation. 8. A : India is one of the mega diversity countries. R : In India there are 3 hot spots.

9. A : Presently sixth mass extinction is going on. R : Human beings are responsible for accelerated extinction.

10. A : At tropics more species are present. R : Tropics are best suited for speciation.

11. A : Diversity plays an important role in ecosystem stability. R : More diverse ecosystem has less variation in year to year biomass production.

12. A : Habitat loss and fragmentation is major cause of biodiversity loss. R : Animals with migratory habits are most affected by fragmentation of habitat.

13. A : Co-extinction is one of the causes of biodiversity loss. R : Extinction of pollinator will lead to extinction of plant.

14. A : Hot spots are characterized by high degree of endemism. R : Hot spot have around 30% of world diversity.

15. A : Sacred groves are helpful in in situ conservation. R : Sacred groves have high degree of endemism.




1. Which of the following represent maximum number of species among global biodiversity? (1) Mosses and Ferns (2) Algae [NEET 2013] (3) Lichens (4) Fungi 2. Which one of the following is not used for ex situ plant conservation? (1) Botanical Gardens (2) Field gene banks [NEET 2013] (3) Seed banks (4) Shifting cultivation 3. Select the correct statement about biodiversity [CBSE AIPMT 2012] (1) The desert areas of Rajasthan and Gujarat have a very high level of desert animal

species as well as numerous rare animals. (2) Large scale planting of Bt cotton has no adverse effect on biodiversity. (3) Western Ghats have a very high degree of species richness and endemism. (4) Conservation of biodiversity is just a fad pursued by the developed countries. 4. India has only 2.4% of the world‟s land area, its share of the global species diversity is (1) 1.8% (2) 3.1 % [AMU 2012] (3) 5.1% (4) 8.1 % 5 Total number of identified biodiversity hot spots in the world are (1) 25 (2) 24 [AMU 2012] (3) 40 (4) 34 6. Kanha national park is located in ............ and is famous for ................ [AMU 2012] (1) Madhya Pradesh, elephant (2) Madhya Pradesh, tiger (3) Odisha, tiger (4) Assam, elephant 7. Silent valley is a tropical evergreen forest located in (1) Kerala (2) Karnataka [MANIPAL 2012] (3) Maharashtra (4) Odisha 8. Which one of the following is not included under in situ conservation? [WB JEE 2012] (1) National park (2) Wild life sanctuary (3) Zoological garden (4) Biosphere reserve 9. Large woody vines are more commonly found in [CBSE AIPMT 2011] (1) Mangroves (2) Tropical rainforests (3) Alpine forests (4) Temperate forests

10. 1°C to 13°C annual variations in the intensity and duration of temperature and 50 to 250 cm annual variation in precipitation, account for the formation of a major biome as [Kerala CEE 2011]

(1) Temperate forest (2) Coniferous forest (3) Tropical forest (4) Grassland 11. Which one of the following expanded forms of the following acronyms is correct? (1) UNEP - United Nations Environmental Policy [CBSE AIPMT 2011] (2) EPA - Environmental Pollution Agency (3) IUCN - International Union for Conservation of Nature and Natural Resources (4) IPCC - International Panel for Climate Change 12. Which one of the following shows maximum genetic diversity in India? (1) Rice (2) Maize [CBSE AIPMT 2011]



(3) Mango (4) Groundnut 13. Total number of all species of organisms in a given region is known as the region‟s (1) Biota (2) Flora [DUMET2011] (3) Fauna (4) Diversity 14. How many bio-geographical regions are present in India? [DUMET2011] (1) 3 (2) 4 (3) 7 (4) 10 15. Kaziranga is famous for [O-JEE 2011] (1) Wild ass (2) Elephant (3) Buffalo (4) Rhinoceros 16. Chipko movement is related to [O-JEE 2011] (1) Swaminathan (2) Bahuguna (3) Odum (4) Misra 17. Which of the following species is restricted to a specific area? [WB JEE 2011] (1) Sibling species (2) Allopatric species (3) Sympatric species (4) Endemic species 18. Which one of the following is an example of ex situ conservation? [CBSE AIPMT 2010] (1) Wildlife sanctuary (2) Seed bank (3) Sacred groves (4) National park 19. The species diversity of plants on earth is [KERALA CEE 2010] (1) 2.4% (2) 22% (3) 8.1% (4) 85% 20. The alien species introduced into lake Victoria that was responsible for the extinction of

Cichlid fishes is [KERALA CEE 2010] (1) African catfish (2) Water hyacinth (3) Carrot grass (4) Nile perch 21. Conservation in natural habitat is [OJEE 2010] (1) in situ (2) ex situ (3) zoo (4) botanic garden 22. The animal, extinct from India is [OJEE 2010] (1) lion (2) cheetah (3) deer (4) peacock 23. A renewable exhaustible natural resource is [CBSE AIPMT 2010] (1) coal (2) petroleum (3) minerals (4) forest 24. Silent valley is tropical evergreen forest located in (1) Kerala (2) Karnataka [AFMC 2009] (3) Maharashtra (4) Orissa



25. Which of the following rain forest is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 of reptiles and more than 125,000 invertebrates? [AIIMS 2009]

(1) Amazonian (2) Nilgiri (3) Arctic tundra (4) Temperate

26. The government of India in 1980s has introduced a concept to work closely with the local communities for protecting and managing forests. The concept is

(1) Forest research institutes [AIIMS 2009] (2) Panel of local communities for forest management (3) Joint forest management (4) Jhum cultivation 27. An inexhaustible, non-conventional universal source of energy is [DUMET 2009] (1) wind energy (2) solar energy (3) hydrothermal energy (4) tidal energy 28. The greatest problem of water conservation is to reduce the amount of [DUMET 2009] (1) precipitation (2) run-off water (3) groundwater (4) evaporation 29. Lime is added to the soil which is too [DUMET 2009] (1) sandy (2) salty (3) alkaline (4) acidic 30. The percentage of forest cover recommended by the national forest policy (1988) is (1) 33% for plains and 67% for hills (2) 37% for plains and 63% for hills (3) 20% for plains and 70% for hills (4) 23% for plains and 77% for hills [KERALA CEE 2009]

31. What is the main cause for the extinction of some species in tropical forest? (1) Deforestation (2) Afforestation [MHT CET 2009] (3) Pollution (4) Soil erosion

32. Which of the following is an inexhaustible resource? [MHT CET 2009] (1) Fossil fuel (2) Solar energy (3) Coal (4) Petroleum

33. Which one is not a renewable natural resource of energy ? [J&K CET 2009] (1) Tidal energy (2) Wind energy (3) Fossil fuels (4) Solar energy

34. Which one of the following has maximum genetic diversity in India? [CBSE AIPMT 2009] (1) Teak (2) Mango (3) Wheat (4) Tea

34. Chipko movement was launched for the protection of (1) Grasslands (2) Forests [CBSE AIPMT 2009] (3) Livestock (4) Wet lands

35. Tiger is not a resident in which one of the following national park? [CBSE AIPMT 2009] (1) Ranthambore (2) Sunderbans (3) Gir (4) Jim Corbett

36. The total number of biodiversity hot spots in the world are [AFMC 2009] (1) 24 (2) 12 (3) 34 (4) 52

37. Which of the following is exotic species? [AFMC 2009] (1) Parthenium (2) Lantana



(3) Eichhornia (4) All of these

38. A historic convention on biological diversity held in Rio de Janerio in 1992 is known as (1) The Earth summit (2) Montreal protocol [AFMC 2009] (3) Geneva convention (4) Janerio convention

39. Biodiversity Act of India was passed by the Parliament in the year [AFMC 2009] (1) 1996 (2) 1992 (3) 2002 (4) 2000

40. Core zone, buffer zone and manipulation zone are found in [BHU 2009] (1) National park (2) Sanctuary (3) Tiger reserve (4) Biosphere reserve

41. One of these is not concerned with wild life conservation. [BHU 2009] (1) IVF (2) IUCN (3) WWF (4) IBWL

42. Largest tiger population is found in [BHU 2009] (1) Sunderban national park (2) Corbett national park (3) Ranthambore national park (4) Kanha national park

43. Biosphere reserve programme started in India in (1) 1986 (2) 1984 [AMU 2009] (3) 1982 (4) 1988

44. The species listed in Red Data Book are [AMU 2009] (1) Threatened (2) Endangered (3) Rare (4) All of these

45. Most of the endangered species are the victims of [MANIPAL 2009] (1) Competition with introduced species (2) Habitat destruction (3) Over-hunting (4) Acid rain

46. The greatest threat to genetic diversity in agricultural crops is [MANIPAL 2009] (1) Extensive use of insecticides and pesticides (2) Extensive mixed cropping (3) Introduction of high yielding varieties (4) Extensive use of fertilizers

47. All the following are included under in situ conservation except [MANIPAL 2009] (1) Botanical garden (2) Biosphere reserve (3) National park (4) Sanctuary

48. A taxon, which is facing an extremely high risk of extinction in the wild in immediate future is known as

(1) Rare (2) Exotic [KERALA CEE 2009] (3) Vulnerable (4) Endangered (e) Critically endangered

49. Which one is an endangered species? [MHT CET 2009] (1) Cuscuta (2) Acacia nilotica (3) Nepenthes (4) Both (2) and (3)

50. The largest endangered bird in India is [HARYANA PMT 2009] (1) Vulture (2) Flamingo (3) Great Indian bustard (4) Great Indian hornbill 51. Gir sanctuary is mainly for [HARYANA PMT 2009]



(1) Rhino (2) Tiger (3) Lion (4) Elephant

52. One of the ex situ conservation method for endangered species is [JCECE 2009] (1) wildlife sanctuaries (2) biosphere reserves (3) cryopreservation (4) national parks

53. The Wildlife Protection Act was introduced in [WB JEE 2009] (1) 1972 (2) 1981 (3) 1986 (4) 1991

54. The Periyar sanctuary is located in [J&K CET 2009] (1) Kerala (2) Tamil Nadu (3) Karnataka (4) Andhra Pradesh

55. Which one of the following contributes to social forestry? [MHT CET 2008] (1) Leucaena leucocephala (2) Mangifera indica (3) Jatropha (4) None of the above

56. Which one of the following is not observed in biodiversity hot spots? [CBSE AIPMT 2008] (1) Endemism (2) Accelerated species loss (3) Lesser interspecific competition (4) Species richness

57. About 70% of total global carbon is found in [CBSE AIPMT 2008] (1) Grasslands (2) Agro-ecosystems (3) Oceans (4) Forests

58. Which one of the following pairs of geographical areas shows maximum biodiversity in our country? [AIIMS 2008]

(1) Sunderbans and Rann of Kutch (2) Eastern ghats and West Bengal (3) Eastern Himalayas and Western Ghats (4) Kerala and Punjab

59. The presence of diversity at the junction of territories of two different habitats is known as (1) Bottle neck effect (2) Edge effect [UP CPMT 2008] (3) Junction effect (4) Pasteur effect

60. Sanjay Gandhi Biological Park is situated in (1) Patna (2) Kanpur [PUNJAB PMET 2008] (3) Delhi (4) Bangaluru

61. Plants like Aegle marmelos, Ocimum sanctum and Ficus religiosa are a group of plants designated as [KCET 2008]

(1) medicinal plant species (2) lesser known food plants (3) traditional food crops (4) sacred species of plants

62. Spot out the zone of our country considered as the hot spot of biodiversity and regarded as the „Cradle of Speciation‟ [KCET 2008]

(1) Western ghats (2) North East (3) Himalayan base (4) Deccan plateau

63. Habitat loss and fragmentation, over exploitation, alien species invasion and co-extinction are causes for [Kerala CEE 2008]

(1) population explosion (2) migration (3) biodiversity loss (4) pollution (e) ecological succession

64. Wildlife conservation aims at



I. Maintaining the ecological process. II. To enrich the wild life diversity with exotic species III. Preventing migration of species. IV. Maintaining the diversity of life. The correct statements are [EAMCET 2008] (1) I, II (2) II, III (3) III, IV (4) I, IV 65. Susceptibility to extinction is due to [MANIPAL 2008] (1) Large body size (2) Small population (3) High trophic level (4) All of these 66. In your opinion, which is the most effective way to conserve the plant diversity of an area?

[MHT CET 2008] (1) By tissue culture method (2) By creating biosphere reserve (3) By creating botanical garden (4) By developing seed bank

67. If we remove half of the forest cover of earth, the crisis that will occur [MHT CET 2008] (1) Many species would become extinct (2) Population, pollution and ecological imbalance will rise (3) Energy crisis will commence (4) The remaining forest will correct the imbalance

68. Identify the correctly matched pair. [MHT CET 2008]

(1) Gir forest Rhino (2) Kaziranga Elephant

(3) Corbett park Aves (4) Rann of Kutch Wild ass

69. One of the most important functions of botanical gardens is that [MHT CET 2008] (1) one can observe tropical plants there (2) they allow ex situ conservation of germplasm (3) they provide the natural habitat for wild life (4) they provide a beautiful area for recreation

70. Estuaries are considered as nutrient rich and [DUMET 2007] (1) poor in biodiversity (2) related to Pond (3) rich in biodiversity (4) having low species numbers

71. In this conservation method, several grasses are left out in soil after the crop is harvested. (1) Contour farming (2) Terrace farming [GUJ CET 2007] (3) Tillage (4) Crop rotation

72. Which one of the following pairs of organisms are exotic species introduced in India? [CBSE AIPMT 2007]

(1) Ficus religiosa, Lantana camara (2) Lantana camara, Water hyacinth (3) Water hyacinth, Prosopis cineraria (4) Nile perch, Ficus religiosa

73. One of endangered species of Indian medicinal plants is that of [CBSE AIPMT 2007] (1) Podophyllum (2) Ocimum (3) Garlic (4) Nepenthes

74. Identify the odd combination of the habitat and the particular animal concerned. [CBSE AIPMT 2007]

(1) Dachigam national park Snow leopard (2) Sunderbans Bengal tiger

(3) Periyar Asiatic Lion (4) Rann of Kutch Wild ass 75. Manas sanctuary is located at [KCET 2007] (1) Rajasthan (2) Assam (3) Bihar (4) Gujarat



76. ….. is the taxon, which is likely to move into endangered category in near future, if conditions prevail as it is. [KCET 2007]

(1) Vulnerable (2) Endanger (3) Rare (4) Extinct 77. Number of wild life is continuously decreasing. What is the main reason of this?

[RPMT 2007] (1) Predation (2) Cutting down of forests (3) Destruction of habitats (4) Hunting

78. Biosphere reserves differ from national parks and wild life sanctuaries because in the former (1) Human beings are not allowed to enter [AIIMS 2006] (2) People are an integral part of the system A (3) Plants are paid greater attention than the animals (4) Living organisms are brought from all over the world and preserved for posterity

79. Excessive accumulation of organic matter in water bodies leads to [DUMET 2006] (1) Decrease in species diversity (2) Increase in species diversity (3) Green house effect (4) No effect on species diversity

80. Species which is in danger of extinction is [JCECE 2006] (1) Endangered (2) Vulnerable (3) Rare (4) Critically endangered

81. Ranthambore national park is situated in [J & K CET 2006] (1) Assam (2) Jharkhand (3) Uttarakhand (4) Rajasthan

82. Siberian cranes are regular visitors of [HARYANA PMT 2005] (1) Bharatpur sanctuary, Rajasthan (2) Lalbagh, Bangaluru (3) Vedanthgol sanctuary, Tamil Nadu (4) Jim Corbett national park, Uttarakhand

83. Minerals, metals and fossil fuels are which type of resources of energy? [AMU 2005] (1) Renewable (2) Non-renewable (3) Biodegradable (4) Degradable

84. Soil conservation is a practice, in which soil [KCET 2005] (1) Is protected from being carried away by wind and water (2) Is well aerated (3) Fertility is enhanced (4) Erosion is allowed

85. Prolonged liberal irrigation of agricultural fields is likely to create the problem of (1) acidity (2) aridity [CBSE AIPMT 2004] (3) metal toxicity (4) salinity

86. According to IUCN red list, what is the status of red Panda (Athurus fulgens)? [CBSE AIPMT 2004]

(1) Vulnerable species (2) Critically endangered species (3) Extinct species (4) Endangered species

87. Biodiversity Act of India was passed by the parliament in the year [CBSE AIPMT 2004] (1) 1996 (2) 1992 (3) 2002 (4) 2000 88. If the Bengal tiger becomes extinct [AIIMS 2004] (1) Hyenas and wolves will become scarce (2) The wild areas will be safe for man and domestic animals (3) Its gene pool will be lost forever



(4) The populations of beautiful animals like deers will get stabilized

89. On the high altitude, birds become rare or extinct, the plants which may disappear along with them are

(1) Pine (2) Oak [AIIMS 2004] (3) Orchids (4) Rhododendrons

90. Which one of the following is a pair of endangered species? [AIlMS 2004] (1) Garden lizard and Mexican poppy (2) Rhesus monkey and sal tree (3) Indian peacock and carrot grass (4) Hornbill and Indian aconite

91. Endemic plants are those, which are [Haryana PMT 2004] (1) cosmopolitan in distribution (2) restricted to grow over certain areas (3) found in Arctic region (4) gregarious in habit

92. Which animal is the symbol of WWF? [Haryana PMT 2004] (1) Tiger (2) Hornbill (3) Giant panda (4) White bear

93. Deforestation causes [MHT CET 2003] (1) Thermal pollution (2) Noise pollution (3) Soil erosion (4) None of these

94. Which group of vertebrates comprises the highest number of endangered species? [CBSE AIPMT 2003]

(1) Reptiles (2) Birds (3) Mammals (4) Fishes

95. Dudhwa national park is in [AMU 2003] (1) Orissa (2) Gujarat (3) Uttar Pradesh (4) Himachal Pradesh

96. The part of earth in which life exists, is known as [Punjab PMET 2003] (1) Lithosphere (2) Biosphere (3) Atmosphere (4) Hydrosphere

97. Rajaji national park is situated in [DUMET 2003] (1) Tamil Nadu (2) Karnataka (3) Uttarakhand (4) Rajasthan

98. The first biosphere reserve established in India for conserving the gene pool of flora and fauna and the life style of tribals is [Kerala CEE 2003]

(1) Nilgiri biosphere reserve (2) Nanda Devi biosphere reserve (3) Uttarakhand biosphere reserve (4) Great Nicobar biosphere reserve (e) Thar biosphere reserve

99. Hangul Project was started by government to save Hangul (Cerrius hanglu) in 1970. The sanctuary where it is started is [Kerala CEE 2003]

(1) National Chambal sanctuary (2) Dachigam sanctuary (3) Corbett national park (4) Bandipur national park

100. An example of ex situ conservation is (AIPMT 2014)

(1) Wildlife Sanctuary (2) Sacred Grove (3) National Park (4) Seed Bank



101. A species facing extremely high risk of extinction the immediate figure is called: (AIPMT 2014)

(1) Critically Endangered (2) Extinct (3) Vulnerable (4) Endemic

102. The organization which publishes the Red List of species is: (AIPMT 2014) (1) UNEP (2) WWF (3) ICFRE (4) IUCN

103. Just as a person moving from Delhi to Shimla to escape the heat for the duration of hot summer, thousands of migratory birds from Siberia and other extremely cold northern regions move to: (AIPMT 2014)

(1) Corbett National Park (2) Keoladeo national Park (3) Western Ghat (4) Meghalaya

104. Cryopreservation of gametes of threatened species in viable and fertile condition can be referred to as: (AIPMT 2015)

(1) Advanced ex situ conservation of biodiversity (2) In situ conservation by sacred groves (3) In situ cryo-conservation of biodiversity (4) In situ conservation of biodiversity

105. Which is National Aquatic Animal of India (NEET Phase -I 2016)

(1) River dolphin (2) Blue whale

(3) Sea- horse (4) Gangetic shark

106. Which of the following is the most important cause of animals and plants being driven to

extinction? (NEET Phase -I 2016)

(1) Alien species invasion (2) Habitat loss and fragmentation

(3) Co-extinctions (4) Over-exploitation

107. How many hot spots of biodiversity in the world have been identified till date? (NEET Phase -II 2016) (1) 17 (2) 25 (3) 34 (4) 43

108. Which of the following is correctly matched? (NEET Phase II 2016)

(1) Aerenchyma – Opuntia

(2) Age pyramid – Biome

(3) Parthenium hysterophorus––Threat to biodiversity

(4) Stratification––Population

109. Red List contains data or information on (NEET Phase -II 2016)

(1) all economically important plants

(2) plants whose products are in international trade

(3) threatened species

(4) marine vertebrates only

110. Which of the following National Parks is home to the famous musk deer or hangul? (NEET Phase -II 2016)

(1) Keibul Lamjao National Park, Manjpur

(2) Bandhavgarh National Park, Madhya Pradesh

(3) Eaglenest Wildlife Sanctuary, Arunachal pradesh

(4) Dachigam National park, Jammu and Kashmir



EXERCISE KEY LEVEL–I(CLASS WORK)

1. (3) 2. (4) 3. (1) 4. (1) 5. (1)

6. (1) 7. (1) 8. (4) 9. (1) 10. (1)

11. (2) 12. (3) 13. (2) 14. (4) 15. (3)

16. (1) 17. (1) 18. (1) 19. (1) 20. (4)

21. (4) 22. (4) 23. (2) 24. (3) 25. (1)

26. (4) 27. (1) 28. (1) 29. (1) 30. (4)


31. (2) 32. (1) 33. (1) 34. (2) 35. (1)

36. (2) 37. (4) 38. (4) 39. (1) 40. (2)

41. (1) 42. (1) 43. (4) 44. (4) 45. (4)

46. (2) 47. (4) 48. (3) 49. (3) 50. (2)

51. (4) 52. (3) 53. (2) 54. (2) 55. (4)

56. (1) 57. (2) 58. (3) 59. (4) 60. (4)


1. (2) 2. (1) 3. (1)

4. (2) 5. (3) 6. (2)

7. (3) 8. (2) 9. (2)

10. (1) 11. (1) 12. (2)

13. (1) 14. (3) 15. (3)


1. (4) 2. (4) 3. (3) 4. (4) 5. (4) 6. (2) 7. (1) 8. (3) 9. (2) 10. (2) 11. (3) 12. (1) 13. (4) 14. (4) 15. (4) 16. (2) 17. (4) 18. (2) 19. (2) 20. (4) 21. (1) 22. (2) 23. (4)

24. (1) 25. (1) 26. (3) 27. (2) 28. (2) 29. (4) 30. (1) 31. (1) 32. (2) 33. (3) 34. (2) 34. (2) 35. (3) 36. (3) 37. (4) 38. (1) 39. (3) 40. (4) 41. (1) 42. (2) 43. (1) 44. (4) 45. (2)

46. (3) 47. (1) 48. (e) 49. (3) 50. (3) 51. (3) 52. (3) 53. (1) 54. (1) 55. (1) 56. (3) 57. (3) 58. (3) 59. (2) 60. (1) 61. (4) 62. (1) 63. (3) 64. (4) 65. (2) 66. (2) 67. (1) 68. (4)

69. (2) 70. (3) 71. (3) 72. (2) 73. (1) 74. (3) 75. (2) 76. (1) 77. (3) 78. (2) 79. (1) 80. (4) 81. (4) 82. (1) 83. (2) 84. (1) 85. (4) 86. (2) 87. (3) 88. (3) 89. (4) 90. (4) 91. (2)

92. (3) 93. (3) 94. (1) 95. (3) 96. (2) 97. (3) 98. (1) 99. (2) 100. (4) 101. (1) 102. (4) 103. (2) 104. (1) 105 (1) 106 (2) 107 (1) 108 (3) 109 (3) 110 (4)

INDEX

Topic Name Page No


Exercise 186-200

Level–I 186-187

Level–II 188-191

Assertion & Reason 192-192


Answers 201-201


Pollution and global environmental change

Air pollution and its control

Smog

Classic smog

Photochemical smog

Acid rain

Control of particulate matter

Controlling vehicular air pollution: a case study of Delhi

Noise pollution

Water pollution and its control

Domestic sewage and industrial effluents

Biomagnification

Eutrophication

Oil spill

A case study of integrated waste water treatment

Solid wastes

Case study of remedy for plastic waste

Agro-chemicals and their effects

Radioactive wastes

Greenhouse effect and global warming

Measures to control global warming

Ozone depletion in the stratosphere

Degradation by improper resource utilisation and maintenance

Deforestation

Consequences of deforestation

ENVIRONMENTAL ISSUES

Environmental Issues Rg.-Bot. XII-19-21


POLLUTION AND GLOBAL ENVIRONMENTAL CHANGE

Human population size has grown enormously over the last hundred years. This means increase

in demand for food, water, home, electricity, roads, automobiles and numerous other

commodities. These demands are exerting tremendous pressure on our natural resources, and are

also contributing to pollution of air, water and soil. The need of the hour is to check the

degradation and depletion of our precious natural resources and pollution without halting the

process of development.

Pollution is any undesirable change in physical, chemical or biological characteristics of air,

land, water or soil. Agents that bring about such an undesirable change are called as pollutants.

In order to control environmental pollution, the Government of India has passed the

Environment (Protection) Act, 1986 to protect and improve the quality of our environment (air,

water and soil).

Pollution causing agents or substances are called pollutants and these pollutants are basically of

two types:

1. Biodegradable or Degradable pollutants or wastes: These are also called non-

conservative pollutants. These are decomposed chemically or by activity of micro-organisms

into harmless products. e.g. sewage and sludge.

2. Non-biodegradable or Conservative or Non-degradable pollutants or wastes : These are

persistent pollutants and are not decomposed naturally or by activity of micro-organisms

and thus are not recycled back into the atmosphere e.g. long chain phenolic compounds,

glass, plastics, aluminium cans, heavy metals like nickel, lead, mercury, chromium and

pesticides like DDT, etc.

AIR POLLUTION AND ITS CONTROL

Air is required for our respiratory needs. Air pollutants cause injury to all living organisms. They

reduce growth and yield of crops and cause premature death of plants. Air pollutants also

deleteriously affect the respiratory system of humans and of animals. Harmful effects depend on

the concentration of pollutants, duration of exposure and the organism.

While major stationary sources are often identified with air pollution, the greatest source of

emissions is actually made up by mobile sources, mainly the automobiles. Gases such as carbon

dioxide, which contribute to global warming, have recently gained recognition as pollutants by

some scientists. Others recognize the gas as being essential to life, and therefore incapable of

being classed as a pollutant.

Smokestacks of thermal power plants, smelters and other industries release particulate and

gaseous air pollutants together with harmless gases, such as nitrogen, oxygen, etc.

Pollutants can be classified as either primary or secondary. Primary pollutants are substances

directly produced by a process, such as ash from a volcanic eruption or the carbon monoxide gas

from a motor vehicle exhaust.

Secondary pollutants are not emitted. Rather, they form in the air when primary pollutants react

or interact. An important example of a secondary pollutant is ground level ozone - one of the

many secondary pollutants that make up photochemical smog.

Note that some pollutants may be both primary and secondary that is, they are both emitted

directly and formed from other primary pollutants.

ENVIRONMENTAL ISSUES



Primary pollutants produced by human activity include:

oxides of sulphur, nitrogen and carbon

organic compounds, such as hydrocarbons (fuel vapours and solvents)

particulate matter, such as smoke and dust

metal oxides, especially those of lead, cadmium, copper and iron

chlorofluorocarbons (CFCs)

hazardous air pollutants (HAP)

persistent organic pollutants (POPs)

odours

Secondary pollutants include some particles formed from gaseous primary pollutants and

compounds in photochemical smog, such as nitrogen dioxide, ground level ozone and

peroxyacyl nitrate (PAN). Secondary pollutants are often more harmful than primary pollutants.

The enhanced effect is called synergism.

(1) Primary air pollutants (which are released directly) are CO, SO2, NOX, (oxides of nitrogen),

H2S, Hydrocarbons, fluorides, CFC‘s, particulate matter, etc.

(i) SO2 affects the plants adversely as follows:

By altering or changing the permeability of membranes by efflux of K+ ions.

SO2 acts as competitive inhibitor of CO2 on RuBP-carboxylase and PEP-carboxylase enzymes

and thus photosynthesis is inhibited.

SO2 causes irritation of eyes, respiratory tract damage, bronchitis, asthma, etc. Maximum SO2

pollution in India occurs in Kolkata.

SO2 has also adverse effect on buildings, sculptures, etc where it causes discoloration and

deterioration. Yellowing and blackening of Taj Mahal at Agra is due to SO2 and other

pollutants released by Mathura refinery, which is called 'Stone Cancer'.

SO2 combines with water in air to form sulphurous acid causing acid rain.

Lichens are sensitive to SO2 and act as pollution indicators.

(ii) CO is released during incomplete combustion of petroleum products and automobiles. It

combines with haemoglobin to produce carboxyhaemoglobin. Carbon monoxide accounts for

50% of total air pollutants. CO reduces oxygen carrying capacity of the blood and thus causes

asphyxiation. Maximum CO concentration is present in Kolkata (35 ppm), followed by

Kanpur (30 ppm) in India.

(iii) Nitrogen oxides (NOx) and SO2 are produced during the combustion of coal (industry) and

petroleum (in automobiles). Lightening in sky also produces NOx naturally. These gases are

highly reactive in air. They rapidly oxidise to acids (sulphuric or nitric), which quickly dissolve

in water and are washed out to the ground as acid rain.

(iv) HF (hydrogen fluoride) is another air pollutant which is released in ceramics industry,

aluminum refineries, etc. High HF concentration causes a disease called fluorosis in animals

including human beings.

(v) Particulate matter like soot, pollen, dust, flyash, etc get deposited in respiratory tract causing

diseases like pneumoconiasis, byssinosis, emphysaema, siderosis, etc. Pollen, dust, etc cause

allergies. SPM is suspended particulate matter (less than 10um). It is highest in Kolkata in

India.

(vi) Lead (Pb) is released by combustion of petrol when added as anti knock agent tetraethyl lead

and disturbs nervous system, liver, kidneys, etc in adults and causes brain damage in children.



(2) Secondary Air Pollutants and their Effects Smog Smog is a kind of air pollution; the word "smog" means a product of smoke and fog. Smog is of

two types, i.e. classical smog and photochemical smog. Classical smog (London smog) is also

known as sulphur smog, because it has excess of sulphur and its main components are smoke,

dust particles, SO2 and H2S. Photochemical smog (Los-Angeles smog) on the other hand is a

yellowish, brown, opaque smog.

Classic smog

Classic smog results due to condensation of water vapours with H2S and SO2 over dust or smoke

particles. It is dark brown, opaque, reducing in nature and occurs at low temperatures. Classical

smog occured in London during 1952.

Photochemical smog

In the 1950s a new type of smog, known as photochemical smog, was first described. This is a

noxious mixture of air pollutants including the following:

o nitrogen oxides, such as nitrogen dioxide

o tropospheric ozone

o volatile organic compounds (VOCs)

o peroxyacyl nitrates (PAN)

o aldehydes

All of these chemicals are usually highly reactive and oxidizing.

Photochemical smog is the chemical reaction of sunlight, nitrogen oxides (NOx) and volatile

organic compounds (VOCs) in the atmosphere, which forms airborne particles (called particulate

matter) and ground- level ozone.

Photochemical smog is of oxidizing nature, has secondary pollutants and is formed at high

temperatures.

Smog is a problem in a number of cities and continues to harm human health. Ground-level

ozone is especially harmful for senior citizens, children, and people with heart and lung

conditions such as emphysema, bronchitis, and asthma.

The classical example of photochemical smog is seen in traffic congested metropolitan cities

where warm conditions and intense solar radiations are present. Photochemical smog is

composed mainly of ozone (O3), peroxyacyl nitrate (PAN) and NOx. It is often called brown air

where solar radiation is intense. In areas or seasons of lesser solar radiation, smog formation is

incomplete and the air is referred to as grey air. Automobile exhaust contains hydrocarbons and

nitrogen oxides and these play an important role in O3 and PAN formation in urban environment.

An erupting volcano can also emit high levels of sulphur dioxide, creating volcanic smog, or vog.

Smog and ozone may damage plant as well as animal life. In plants, the main damage occurs in

leaves. Ozone aggravates lung diseases. PAN damages chloroplasts and thus, the photosynthetic

efficiency and growth of plants are reduced.

Acid Rain

Acid rain : The term acid rain also known as acid precipitation is commonly used for the

deposition of acidic components in rain, snow, dew, or dry particles. The more accurate term is

"acid precipitation." Acid rain occurs when sulphur dioxide and nitrogen oxides are emitted



into the atmosphere, undergo chemical transformations and are absorbed by water droplets in

clouds.

Acid rain is defined as any type of precipitation with a pH that is unusually low. Acid rain

accelerates weathering in carbonate rocks and accelerates building weathering. It also contributes

to acidification of rivers, streams, and forest damage at high elevations. When the acid builds up

in rivers and streams it can kill fish.

Evidence for an increase in the levels of acid rain comes from analysing layers of glacial ice.

These have shown a sudden decrease in pH from the start of the Industrial Revolution.

The most important gas which leads to acid rain is sulphur dioxide.

Control of Particulate matter

Electrostatic precipitator

There are several ways of removing particulate matter. Arresters are devices used to separate

particulate pollutants. These include separators, settling chambers, filters, etc. These pollutants

must be separated / filtered out before releasing the harmless gases into the atmosphere; the most

widely used method is the electrostatic precipitator, which can remove over 99 per cent

particulate matter present in the exhaust from a thermal power plant. It has electrode wires that

are maintained at several thousand volts, which produce a corona that releases electrons. These

electrons attach to dust particles giving them a net negative charge. The collecting plates are

grounded and attract the charged dust particles. The velocity of air between the plates must be

low enough to allow the dust to fall. Particulate matter that are very small are not removed by

these precipitators.

A scrubber can remove gases like sulphur dioxide. In a scrubber, the exhaust is passed through a

spray of water or lime.

According to Central Pollution Control Board (CPCB), particulate size 2.5 micrometers or less

in diameter (PM 2.5) are responsible for causing the greatest harm to human health. These fine

particulates can be inhaled deep into the lungs and can cause breathing and respiratory

symptoms, irritation, inflammations and damage to the lungs and premature death.

Automobiles are a major cause for atmospheric pollution atleast in the metro cities. As the

number of vehicles increase on the streets, this problem is now shifting to the other cities too.

Proper maintenance of automobiles along with use of lead-free petrol or diesel can reduce the

pollutants they emit.

Catalytic converters, having expensive metals namely platinum-palladium and rhodium as

the catalysts, are fitted into automobiles for reducing emission of poisonous gases. As the exhaust


PACE IIT & MEDICAL: Delhi & NCR / MUMBAI / LUCKNOW / GOA / Akola / Kolkata / Indore / Nashik / Pune / Nagpur / Bokaro / Durgapur / Ahmedabad / Bhopal / Dubai 176

passes through the catalytic converter, unburnt hydrocarbons are converted into carbon dioxide

and water, and carbon monoxide and nitric oxide are changed to carbon dioxide and nitrogen gas,

respectively. Motor vehicles equipped with catalytic converter should use unleaded petrol

because lead in the petrol inactivates the catalyst.

Controlling Vehicular Air Pollution: A Case Study of Delhi Delhi leads the country in its levels of air-pollution – it has more cars than the states of Gujarat

and West Bengal put together. In the 1990s, Delhi ranked fourth among the 41 most polluted

cities of the world.

Air pollution problems in Delhi became so serious that a public interest litigation (PIL) was filed

in the Supreme Court of India. After being censured very strongly by the Supreme Court, under

its directives, the government was asked to take, within a specified time period, appropriate

measures, including switching over the entire fleet of public transport, i.e. buses, from diesel to

compressed natural gas (CNG).

All the buses of Delhi were converted to run on CNG by the end of 2002.

CNG burns efficiently, unlike petrol or diesel, in the automobiles and very little of it is left

unburnt. Moreover, CNG is cheaper than petrol or diesel, cannot be siphoned off by thieves and

adulterated like petrol or diesel. The main problem with switching over to CNG is the difficulty

of laying down pipelines to deliver CNG through distribution points/pumps and ensuring

uninterrupted supply.

Simultaneously parallel steps taken in Delhi for reducing vehicular pollution include phasing out

of old vehicles, use of unleaded petrol, use of low-sulphur petrol and diesel, use of catalytic

converters in vehicles, application of stringent pollution level norms for vehicles, etc.

The Government of India through a new auto fuel policy has laid out a roadmap to cut down

vehicular pollution in Indian cities. More stringent norms for fuels means steadily reducing the

sulphur and aromatics content in petrol and diesel fuels.

Euro II norms, for example, stipulate that sulphur be controlled at 350 parts-per-million (ppm) in

diesel and 150 ppm in petrol. Aromatic hydrocarbons are to be contained at 42 per cent of the

concerned fuel. The goal, according to the roadmap, is to reduce sulphur to 50 ppm in petrol and

diesel and bring down the level to 35 per cent.

Corresponding to the fuel, vehicle engines will also need to be upgraded. The Bharat Stage II

(equivalent to Euro-II norms), which is currently in place in Delhi, Mumbai, Kolkata, Chennai,

Bangalore, Hyderabad, Ahmedabad, Pune, Surat, Kanpur and Agra, is applicable to all

automobiles throughout the country from April 1, 2005. All automobiles and fuel-petrol and

diesel vehicles–were to have met the Euro III emission specifications in these 11 cities from

April 1, 2005 and the Euro-IV norms by April 1, 2010. The rest of the country were to have

Euro-III emission norm compliant automobiles and fuels by 2010.

Thanks to the efforts made, the air quality of Delhi has significantly improved. According to an

estimate, a substantial fall in CO2 and SO2 level has been found in Delhi between 1997 and 2005.

Noise Pollution

In India, the Air (Prevention and Control of Pollution) Act came into force in 1981, but was

amended in 1987 to include noise as an air pollutant. Noise is undesired high level of sound.

Unit of sound level is decibel.

Noise causes psychological and physiological disorders in humans.

A brief exposure to extremely high sound level, 150 dB or more generated by takeoff of a jet

plane or rocket, may damage ear drums thus permanently impairing hearing ability.



Even chronic exposure to a relatively lower noise level of cities may permanently damage

hearing abilities of humans. Noise also causes sleeplessness, increased heart beat, altered

breathing pattern, thus considerably stressing humans.

Reduction of noise in our industries can be affected by use of sound absorbent materials or by

muffling noise. Stringent following of laws laid down in relation to noise like delimitation of

horn-free zones around hospitals and schools, permissible sound-levels of crackers and of

loudspeakers, timings after which loudspeakers cannot be played, etc. need to be enforced to

protect ourselves from noise pollution.

Rows of trees or green vegetation grown along roadside to absorb noise is termed as green

muffler.

The Central Pollution Control Board has recommended zone-wise ambient noise levels as given

in Table

Zones Day (0600 - 2100 hrs) Night (2100 - 0600 hrs) Industry 75 dB 80 dB

Commercial 65 dB 55 dB

Residential 55 dB 45 dB

Silent zone 50 dB 40 dB

WATER POLLUTION AND ITS CONTROL

Water pollution is mainly caused by industrial wastes, sewage (household waste), insecticides,

herbicides, rodenticides, etc.

Waste water quality indicators such as the biochemical oxygen demand (BOD) and the chemical

oxygen demand (COD) are essentially laboratory tests to determine whether or not a specific

wastewater will have a significant adverse effect upon fish or upon aquatic plant life.

Keeping in mind importance of maintaining the cleanliness of the water bodies, the Government

of India has passed the Water (Prevention and Control of Pollution) Act, 1974 to safeguard

our water resources.

Domestic Sewage and Industrial Effluents A mere 0.1 per cent impurities

make domestic sewage unfit for

human use. Solids are relatively

easy to remove; what is difficult to

remove are dissolved salts such as

nitrates, phosphates, and other

nutrients, and toxic metal ions and

organic compounds.

Composition of waste water

Domestic sewage primarily contains biodegradable organic matter, which readily decomposes

thanks to bacteria and other micro-organisms, which can multiply using these organic substances

as substrates and hence utilise some of the components of sewage.

It is possible to estimate the amount of organic matter in sewage water by measuring

Biochemical Oxygen Demand (BOD). BOD is the oxygen in mgs required for 5 days in one

litre of water at 20°C for micro organisms to metabolise organic wastes. BOD levels below

1500mg/L->low pollution, 1500-4000mg/L->medium pollution and above 4000mg/L->high

organic pollution.

DO stands for dissolved oxygen DO below 8mg/L indicates pollution, below 4mg/L heavy

pollution.



COD is the amount of oxygen required to oxidise all reducing substances present in water.

Effect of sewage discharge on some important characteristics of a river

This Figure shows some of the changes that take place following discharge of sewage into a

river.

Micro-organisms involved in biodegradation of organic matter in the receiving water body

consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream

from the point of sewage discharge. This causes mortality of fish and other aquatic creatures.

Presence of large amounts of nutrients in waters also causes excessive growth of planktonic

(free-floating) algae, called an algal bloom which imparts a distinct colour to the water bodies.

Algal blooms cause deterioration of the water quality and fish mortality. Some bloom-forming

algae are extremely toxic to human beings and animals.

Beautiful mauve-coloured flowers are

found on very appealingly-shaped

floating plants in water bodies. These

plants which were introduced into India

for their lovely flowers have caused

havoc due to their excessive growth by

causing blocks in our waterways. They

grow faster than our ability to remove

them. These are plants of water hyacinth

(Eichhornia crassipes), the world‘s

most problematic aquatic weed, also

called ‘Terror of Bengal’. They grow

abundantly in eutrophic water bodies,

and lead to an imbalance in the

ecosystem dynamics of the water body.

Pictorial view of an algal bloom

Sewage from our homes as well from hospitals are likely to contain many undesirable pathogenic

microorganisms, and its disposal into a water without proper treatment may cause outbreak of

serious diseases, such as, dysentery, typhoid, jaundice, cholera, etc.

Unlike domestic sewage, waste water from industries like petroleum, paper manufacturing, metal

extraction and processing, chemical manufacturing, etc. often contain toxic substances, notably,



heavy metals (defined as elements with density > 5 g/cm3 such as mercury, cadmium, copper,

lead, etc.) and a variety of organic compounds.

Mercury contamination led to Minamata disease in Japan which affected neuro muscular system

of humans.

Cadmium toxicity in water may lead to painful skeletal deformities called itai-itai first reported in

Japan. Excessive use of nitrate fertilisers may lead to formation of met-haemoglobin in humans

reducing oxygen transport. In infants it causes blue baby syndrome.

Biomagnification

The toxic substances, often present in industrial waste waters, can

undergo biological magnification (Biomagnification) in the aquatic

food chain.

Biomagnification refers to increase in concentration of the toxicant at

successive trophic levels.

This happens because a toxic substance like heavy metal or persistent

pesticide accumulated by an organism cannot be metabolised or

excreted, and is thus passed on to the next higher trophic level. This

phenomenon is well-known for mercury and DDT.

Figure shows biomagnification of DDT in an aquatic food chain. In

this manner, the concentration of DDT is increased at successive

trophic levels; say if it starts at 0.003 ppb (ppb = parts per billion) in

water, it can ultimately can reach 25 ppm (ppm = parts per million) in

fish-eating birds, through biomagnification.

High concentrations of DDT disturb calcium metabolism in birds,

which causes thinning of eggshell and their premature breaking,

eventually causing decline in bird populations.

EUTROPHICATION

Eutrophication is the natural aging of a lake by biological enrichment of its water. In a young

lake the water is cold and clear, supporting little life. With time, streams draining into the lake

introduce nutrients such as nitrogen and phosphorus, which encourage the growth of aquatic

organisms. As the lake‘s fertility increases, plant and animal life burgeons, and organic remains

begin to be deposited on the lake bottom. Over the centuries, as silt and organic debris pile up,

the lake grows shallower and warmer, with warm-water organisms supplanting those that thrive

in a cold environment. Marsh plants take root in the shallows and begin to fill in the original lake

basin. Eventually, the lake gives way to large masses of floating plants (bog), finally converting

into land. Depending on climate, size of the lake and other factors, the natural aging of a lake

may span thousands of years. However, pollutants from man‘s activities like effluents from the

industries and homes can radically accelerate the aging process. This phenomenon has been

called Cultural or Accelerated Eutrophication. During the past century, lakes in many parts of

the earth have been severely eutrophied by sewage and agricultural and industrial wastes.

The prime contaminants are nitrates and phosphates, which act as plant nutrients. They

overstimulate the growth of algae, causing unsightly scum and unpleasant odours, and rob the

water of dissolved oxygen vital to other aquatic life. At the same time, other pollutants flowing

into a lake may poison whole populations of fish, whose decomposing remains further deplete

the water‘s dissolved oxygen content. In such fashion, a lake can literally choke to death.



Oil spill

An oil spill or oil slick is the unintentional release of liquid petroleum hydrocarbon into the

environment as a result of human activity. The term often refers to marine oil spills, where oil is

released into the ocean or coastal waters.

A heavy oil spill across the shore blankets rock-pools etc harm life by preventing gas exchange

and eliminating light as well as directly leaching toxins into the water.

Seabirds are adversely affected as the oil penetrates and opens up the structure of their plumage,

so they become chilled, lose the ability to fly, and lose their buoyancy in water.

Heated (thermal) wastewaters flowing out of electricity-generating units, e.g. thermal power

plants, constitute another important category of pollutants. Thermal wastewater eliminates or

reduces the number of organisms sensitive to high temperature, and may enhance the growth of

plants and fish in extremely cold areas but, only after causing damage to the indigenous flora and

fauna.

A Case Study of Integrated Waste Water Treatment

Wastewater including sewage can be treated in an integrated manner, by utilising a mix of

artificial and natural processes. An example of such an initiative is the town of Arcata, situated

along the northern coast of California. Collaborating with biologists from the Humboldt State

University, the townspeople created an integrated waste water treatment process within a natural

system.

The cleaning occurs in two stages – (1) the conventional sedimentation, filtering and chlorine

treatments are given. After this stage, lots of dangerous pollutants like dissolved heavy metals

still remain. (2) the biologists developed a series of six connected marshes over 60 hectares of

marshland. Appropriate plants, algae, fungi and bacteria were seeded into this area, which

neutralise, absorb and assimilate the pollutants. Hence, as the water flows through the marshes, it

gets purified naturally.

The marshes also constitute a sanctuary, with a high level of biodiversity in the form of fishes,

animals and birds that now reside there. A citizens group called Friends of the Arcata Marsh

(FOAM) are responsible for the upkeep and safeguarding of this wonderful project.

Ecological sanitation is a sustainable system for handling human excreta, using dry composting

toilets. This is a practical, hygienic, efficient and cost-effective solution for human waste

disposal. The key point to note here is that with this composting method, human excreta can be

recycled into a resource (as natural fertiliser), which reduces the need for chemical fertilisers.

There are working ‗EcoSan’ toilets in many areas of Kerala and Sri Lanka.

SOLID WASTES

Solid wastes refer to everything that goes out in trash. Municipal solid wastes are wastes from

homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the

municipality. The municipal solid wastes generally comprise paper, food wastes, plastics, glass,

metals, rubber, leather, textile, etc. Burning reduces the volume of the wastes, although it is

generally not burnt to completion and open dumps often serve as the breeding ground for rats and

flies.

Sanitary landfills were adopted as the substitute for open-burning dumps. In a sanitary landfill,

wastes are dumped in a depression or trench after compaction, and covered with dirt everyday.

Landfills are also not really much of a solution since the amount of garbage generation especially

in the metros has increased so much that these sites are getting filled too. Also there is danger of

seepage of chemicals, etc., from these landfills polluting the underground water resources.



All waste that we generate can be categorised into three types – (1) bio-degradable, (2)

recyclable and (3) the non-biodegradable. It is important that all garbage generated is sorted.

What can be reused or recycled should be separated out. The biodegradable materials can be put

into deep pits in the ground and be left for natural breakdown. That leaves only the non-

biodegradable to be disposed off. The need to reduce our garbage generation should be a prime

goal.

Case Study of Remedy for Plastic Waste

A plastic sack manufacturer in Bangalore has managed to find the ideal solution to the ever-

increasing problem of accumulating plastic waste. Ahmed Khan, aged 57 years old, has been

producing plastic sacks for 20 years. About 8 years ago, he realised that plastic waste was a real

problem.

Polyblend, a fine powder of recycled modified plastic, was developed then by his company. This

mixture is mixed with the bitumen that is used to lay roads. In collaboration with R.V. College of

Engineering and the Bangalore City Corporation, Ahmed Khan proved that blends of

Polyblend and bitumen, when used to lay roads, enhanced the bitumen‘s water repellant

properties, and helped to increase road life by a factor of three.

Hospitals generate hazardous wastes that contain disinfectants and other harmful chemicals, and

also pathogenic micro-organisms. Such wastes also require careful treatment and waste disposal.

The use of incinerators is crucial to disposal of hospital waste.

Irreparable computers and other electronic goods are known as electronic wastes (e-wastes). E-

wastes are buried in landfills or incinerated. Over half of the e-wastes generated in the

developed world are exported to developing countries, mainly to China, India and Pakistan,

where metals like copper, iron, silicon, nickel and gold are recovered during recycling process.

Unlike developed countries, which have specifically built facilities for recycling of e-wastes,

recycling in developing countries often involves manual participation thus exposing workers to

toxic substances present in e-wastes. Eventually recycling is the only solution for the treatment of

e-wastes provided it is carried out in an environment-friendly manner.

AGRO-CHEMICALS AND THEIR EFFECTS

As a result of green revolution, use of inorganic fertilisers and pesticides has increased manifold

for enhancing crop production. Pesticides, herbicides, fungicides, etc., are being increasingly

used. These incidentally, are also toxic to non-target organisms, that are important components of

the soil ecosystem.

Integrated organic farming is a cyclical, zero-waste procedure, where waste products from one

process are cycled in as nutrients for other processes. This allows the maximum utilisation of

resources and increases the efficiency of production.

There is no need to use chemical fertilisers for crops, as cattle excreta (dung) are used as manure.

Crop waste is used to create compost, which can be used as a natural fertiliser or can be used to

generate natural gas for satisfying the energy needs of the farm.

RADIOACTIVE WASTES

Initially, nuclear energy was hailed as a non-polluting way for generating electricity. Later on, it

was realised that the use of nuclear energy has two very serious inherent problems. The first is

accidental leakage, as occurred in the Three Mile Island and Chernobyl incidents and the second

is safe disposal of radioactive wastes.

Chief source of radioactive pollution is nuclear-explosions which release long-lived and short-

lived radioactive substances, e.g. Sr-90, Cs-137, C-14, CO-60, Ru-106, etc.

These radioactive fallouts or nuclear fallouts cause air, water and soil pollution.



Most important long lived radioactive substance released in nuclear explosions is Sr-90, which

accumulate in bone-marrow and cause cancer (leukaemia or blood cancer), genetic disorders and

other deformities. Cs-137 accumulates in muscles and causes muscular pain.

Radiation, that is given off by nuclear waste is extremely damaging to biological organisms,

because it causes mutations to occur at a very high rate. At high doses, nuclear radiation is lethal

but at lower doses, it creates various disorders, the most frequent of all being cancer. Therefore,

nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution.

It has been recommended that storage of nuclear waste, after sufficient pre-treatment, should be

done in suitably shielded containers buried within the rocks, about 500 m deep below the earth‘s

surface.

GREENHOUSE EFFECT AND GLOBAL WARMING The term ‗Greenhouse effect’ has been derived from a phenomenon that occurs in a greenhouse.

It looks like a small glass house and is used for growing plants especially during winter. In a

greenhouse the glass panel lets the light in, but does not allow heat to escape. Therefore, the

greenhouse warms up.

The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of

Earth‘s surface and atmosphere, without greenhouse effect the average temperature at surface of

Earth would have been a chilly –18°C rather than the present average of 15°C.

Clouds and gases reflect about one-fourth of the incoming solar radiation, and absorb some of it

but almost half of incoming solar radiation falls on Earth‘s surface heating it, while a small

proportion is reflected back.

Earth‘s surface re-emits heat in the form of infrared

radiation but part of this does not escape into space as

atmospheric gases (e.g. carbon dioxide, methane,

etc.) absorb a major fraction of it. The molecules of

these gases radiate heat energy, and a major part of

which again comes to Earth‘s surface, thus heating it

up once again. This cycle is repeated many a times.

The above-mentioned gases – carbon dioxide and

methane are commonly known as greenhouse gases

because they are responsible for the greenhouse

effect.

Increase in the level of greenhouse gases has led to considerable heating of Earth leading to

global warming. During the past century, the temperature of Earth has increased by 0.6°C, most

of it during the last three decades.



Scientists believe that this rise in temperature is leading to deleterious changes in the

environment and resulting in odd climatic changes (e.g. El Nino effect), thus leading to increased

melting of polar ice caps as well as of other places like the Himalayan snow caps. Over many

years, this will result in a rise in sea level that can submerge many coastal areas.

Measures to control global warming

The measures include cutting down use of fossil fuel, improving efficiency of energy usage,

reducing deforestation, planting trees and slowing down the growth of human population.

International initiatives are also being taken to reduce the emission of greenhouse gases into the

atmosphere.

Earth summit (1992): It was held in Rio-de-Janeiro to adopt recommendations of CCC for

reducing greenhouse gases. These were signed by 154 nations.

Kyoto Protocol (Dec. 1997): International conference held in Kyoto, Japan obtained commitments from different countries for reducing overall greenhouse gas emissions at a

level 5% below 1990 level by 2008-2012.

OZONE DEPLETION IN THE STRATOSPHERE

‘Bad’ ozone is formed in the lower atmosphere

(troposphere) and harms plants and animals.

There is ‘good’ ozone also; this ozone is found

in the upper part of the atmosphere called the

stratosphere, and it acts as a shield, absorbing

ultraviolet radiation from the sun. UV rays are

highly injurious to living organisms since DNA

and proteins of living organisms preferentially

absorb UV rays, and its high energy breaks the

chemical bonds within these molecules. The

thickness of the ozone in a column of air from

the ground to the top of the atmosphere is

measured in terms of Dobson units (DU).

Ozone hole is the area above Antarctica, where the

ozone layer is the thinnest. Ozone thickness is given in

Dobson unit. The ozone hole over Antarctica develops

each year between late August and early October.

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also

degraded into molecular oxygen in the stratosphere. There should be a balance between

production and degradation of ozone in the stratosphere. Of late, the balance has been disrupted

due to enhancement of ozone degradation by chlorofluorocarbons (CFCs).

CFCs find wide use as refrigerants. CFCs discharged in the lower part of atmosphere move

upward and reach stratosphere. In stratosphere, UV rays act on them releasing Cl atoms. Cl

degrades ozone releasing molecular oxygen, with these atoms acting merely as catalysts; Cl

atoms are not consumed in the reaction. Hence, whatever CFCs are added to the stratosphere,

they have permanent and continuing affects on ozone levels. Although ozone depletion is

occurring widely in the stratosphere, the depletion is particularly marked over the Antarctic

region. This has resulted in formation of a large area of thinned ozone layer, commonly called as

the ozone hole.

UV radiation of wavelengths shorter than UV-B, are almost completely absorbed by Earth‘s

atmosphere, given that the ozone layer is intact. But, UV-B damages DNA and mutation may

occur. It causes aging of skin, damage to skin cells and various types of skin cancers.

In human eye, cornea absorbs UV-B radiation, and a high dose of UV-B causes inflammation of

cornea, called snow-blindness cataract, etc. Such exposure may permanently damage the cornea.



Recognising the deleterious affects of ozone depletion, an international treaty, known as the

Montreal Protocol, was signed at Montreal (Canada) in 1987 (effective in 1989) to control the

emission of ozone depleting substances. Subsequently many more efforts have been made and

protocols have laid down definite roadmaps, separately for developed and developing countries,

for reducing the emission of CFCs and other ozone depleting chemicals.

Helsinki Declaration (May 1989)-Montreal Protocol was ratified by 82 nations at Helsinki. They

pledged to phase out CFCs by 2000.

DEGRADATION BY IMPROPER RESOURCE UTILISATION AND MAINTENANCE

The degradation of natural resources can occur, not just by the action of pollutants but also by

improper resource utilisation practices.

Soil erosion and desertification: The development of the fertile top-soil takes centuries. But, it

can be removed very easily due to human activities like over-cultivation, unrestricted grazing,

deforestation and poor irrigation practices, resulting in arid patches of land. When large barren

patches extend and meet over time, a desert is created. Internationally, it has been recognised that

desertification is a major problem nowadays, particularly due to increased urbanisation.

Waterlogging and soil salinity: Irrigation without proper drainage of water leads to

waterlogging in the soil. Besides affecting the crops, waterlogging draws salt to the surface of the

soil. The salt then is deposited as a thin crust on the land surface or starts collecting at the roots

of the plants. This increased salt content is inimical to the growth of crops and is extremely

damaging to agriculture. Waterlogging and soil salinity are some of the problems that have come

in the wake of the Green Revolution.

DEFORESTATION

Deforestation is the conversion of forested areas to non-forested ones. According to an estimate,

almost 40 per cent forests have been lost in the tropics, compared to only 1 per cent in the

temperate region. The present scenario of deforestation is particularly grim in India. At the

beginning of the twentieth century, forests covered about 30 per cent of the land of India. By the

end of the century, it shrunk to 19.4 per cent, whereas the National Forest Policy (1988) of

India has recommended 33 per cent forest cover for the plains and 67 per cent for the hills.

A number of human activities contribute to deforestation. One of the major reasons is the

conversion of forest to agricultural land so as to feed the growing human population. Trees are

axed for timber, firewood, cattle ranching and for several other purposes.

Slash and burn agriculture, commonly called as Jhum cultivation in the north-eastern states of

India, has also contributed to deforestation. In slash and burn agriculture, the farmers cut down

the trees of the forest and burn the plant remains. The ash is used as a fertiliser and the land is

then used for farming or cattle grazing. After cultivation, the area is left for several years so as to

allow its recovery. The farmers then move on to other areas and repeat this process. In earlier

days, when Jhum cultivation was in prevalence, enough time-gap was given such that the land

recovered from the effect of cultivation. With increasing population, and repeated cultivation,

this recovery phase is done away with, resulting in deforestation.

CONSEQUENCES OF DEFORESTATION

One of the major effects is enhanced carbon dioxide concentration in the atmosphere because

trees that could hold a lot of carbon in their biomass are lost with deforestation. Deforestation



also causes loss of biodiversity due to habitat destruction, disturbs hydrologic cycle, causes soil

erosion, and may lead to desertification in extreme cases.

Reforestation is the process of restoring a forest that once existed but was removed at some

point of time in the past. Reforestation may occur naturally in a deforested area. However, we

can be speed reforestation up by planting trees with due consideration to biodiversity that earlier

existed in that area.

Case Study of People’s Participation in Conservation of Forests

People‘s participation has a long history in India. In 1731, the king of Jodhpur in Rajasthan asked

one of his ministers to arrange wood for constructing a new palace. The minister and workers

went to a forest near a village, inhabited by Bishnois, to cut down trees. The Bishnoi community

is known for its peaceful co-existence with nature. The effort to cut down trees by the kings was

thwarted by the Bishnois. A Bishnoi woman Amrita Devi showed exemplary courage by hugging

a tree and daring king‘s men to cut her first before cutting the tree. The tree mattered much more

to her than her own life. Sadly, the king‘s men did not heed to her pleas, and cut down the tree

along with Amrita Devi. Her three daughters and hundreds of other Bishnois followed her, and

thus lost their lives saving trees. Nowhere in history do we find a commitment of this magnitude

when human beings sacrificed their lives for the cause of the environment. The Government of

India has recently instituted the Amrita Devi Bishnoi Wildlife Protection Award for

individuals or communities from rural areas that have shown extraordinary courage and

dedication in protecting wildlife.

Chipko Movement of Garhwal Himalayas: In 1974, local women showed enormous bravery in

protecting trees from the axe of contractors by hugging them. People all over the world have

acclaimed the Chipko movement realising the significance of participation by local communities.

Social Forestry aims at raising quick growing multipurpose plants in common village lands to

meet demands of timber, fuel wood, fodder, etc.

Agroforestry aims at raising multipurpose plants/trees along with crops for meeting demands of

community.

The Government of India in 1980‘s has introduced the concept of Joint Forest Management

(JFM) so as to work closely with the local communities for protecting and managing forests. In

return for their services to the forest, the communities get benefit of various forest products (e.g.

fruits, gum, rubber, medicine, etc.), and thus the forest can be conserved in a sustainable manner.

————



EXERCISE # LEVEL–I(CLASS WORK)

1. The phenomenon by which certain pollutants (e.g. DDT) accumulate in body tissue in

increasing concentration is called

(1) Biological magnification (2) Biological reduction

(3) Bio-precipitation (4) Bio-degradation

2. In an aquatic food chain polluted by DDT, the tissue concentration of DDT would be highest

in

(1) Aquatic weed (2) Herbivorous fish (3) Carnivores fish (4) Bird feeding on fish

3. Algal bloom is caused by

(1) Availability of excess nutrients (2) Lack of nutrients

(3) Increase in non-biodegradable pollutants (4) Decreased BOD

4. Minamata disease is caused due to contamination by

(1) Hg (2) Pb (3) Cd (4) As

5. Increasing skin cancer and high mutation rate are the result of

(1) Ozone depletion (2) Acid rain (3) CO pollution (4) CO2 pollution

6. Of the following, pick out the constituents of a photochemical smog

A. Ozone B. Nitrogen oxides C. PAN D. H2SO4 E. DDT

F. BHC G. CO2

(1) A, B, C (2) A, B, C, G (3) B, C, D, G (4) A, B, C, E, F, G

7. Environment Protection Act, to protect and improve the quality of our environmental air,

water and soil was passed in the year

(1) 1971 (2) 1974 (3) 1981 (4) 1986

8. In Effluent Treatment Plants (ETPs), at which stage microorganism treatment is provided?

(1) Primary (2) Secondary

(3) Tertiary (4) Microorganisms are not used in ETPs

9. In treatment of waste water, biological treatment is -

(1) Secondary treatment (2) Primary treatment

(3) Tertiary treatment (4) Reverse osmosis stage

10. By what degrees has the mean global temperature increased in the 20th century?

(1) 0.2°C (2) 0.4°C (3) 0.6°C (4) 0.8°C

11. Which is a non-degradable pollutant?

(1) Smoke (2) Polythene (3) Copper scraps (4) Iron scraps

12. Which of the following is a natural pollutant?

(1) Smog (2) Volcanic gases (3) Strong wind (4) Gale



13. As the organic waste input in a water body increases,

(1) BOD increases (2) BOD decreases

(3) BOD may increase or decrease (4) Cannot be said with surety

14. Pick out the correct choice from the following

(1) As BOD increases, DO increases (2) As BOD increases, DO decreases

(3) It depends on the water body and the surrounding environment

(4) No such relation exists between BOD & DO

15. During the past 150 years the concentration of CO, has increased approximately from -

(1) 200 ppm to 300 ppm (2) 120 ppm to 280 ppm

(3) 280 ppm to 360 ppm (4) 350 ppm to 450 ppm

16. The process of nutrient enrichment of water is called as .

(1) Eutrophication (2) Stratification (3) Atrophication (4) Biomagnification

17. When and where the Ozone hole was discovered?

(1) 1985, Antarctica (2) 1985, Arctic (3) 1987, Arctic (4) 1987, Antarctica

18. The Earth Summit, 1992, was held at

(1) Rio de Janeiro (2) Kyoto (3) St. Petersburg (4) Washington

19. In India, Jhum cultivation is practiced mainly in

(1) North East states (2) Gangetic plains (3) Western Ghats (4) Deccan plateau

20. Thickness of ozone is measured in

(1) Decibel (2) Dozen (3) Dobson (4) Meter

21. "Good ozone" is found in the:

(1) Mesosphere (2) Troposphere (3) Stratosphere (4) Ionosphere

22. Lichens indicate SO2, pollution because they

(1) Show association between algae and fungi

(2) Grow faster than others

(3) Are sensitive to SO2

(4) Flourish in SO2 rich environment

23. Which of the following is correct about "El Nino effect"?

(1) temperature rise leads to odd climatic changes

(2) cutting down the use of fossil fuels effects climate.

(3) planting trees effects climate.

(4) slowing down the growth of human population.

24. Which of the following is/are correct regarding Montreal Protocol?

(i) To control persistent organic pollutants.

(ii) To control global warming and climate change.

(iii)To control the emission of ozone depleting substances.

(iv) Biosafety of genetically modified organisms.

(1) (ii) & (iii) (2) (iii) only (3) (iii) & (iv) (4) (i)&(iii)



LEVEL-II(HOME WORK)

1. In India, the Air (Prevention and Control of Pollution) Act came into force in 1981 but was

amended in 1987 to include

(1) thermal pollution (2) radioactive pollution

(3) noise pollution (4) ozone pollution.

2. Match column I with column II and select the correct option.

Column I Column II

(1) Catalytic converter (i) Particulate matter

(2) Electrostatic precipitator (ii) Carbon monoxide and nitrogen oxides

(3) Earmuffs (iii) High noise level

(4) Land fills (iv) Solid wastes

A B C D

(1) (i) (ii) (iii) (iv)

(2) (ii) (i) (iii) (iv)

(3) (iv) (iii) (ii) (i)

(4) (iii) (ii) (iv) (i)

3. ______ are used in electrostatic precipitators.

(1) Catalysts (2) Absorbers (3) Electrodes (4) Chemicals

4. Biological oxygen demand of ______ is the least.

(1) sewage (2) sea water (3) pure water (4) polluted water

5. Due to eutrophication ________

(1) water gets less polluted (2) BOD decreases

(3) algae are destroyed (4) BOD increases

6. ______ is the first step of sewage treatment.

(1) Precipitation (2) Chlorination (3) Sedimentation (4) Aeration

7. Pollution in big cities can be controlled to a large extent by -

(1) Improving traffic condition and road.

(2) Road side plantation

(3) Proper disposal of garbage and domestic as well as municipal wastes.

(4) Cannot be controlled

(1) A, B (2) A, B, C (3) A, D (4) A. B, C, D

8. Primary pollutants used in the synthesis of photochemical smog are -

(1) Unsaturated HCs (2)Oxides of nitrogen (3) Ozone (4) Both a and b

9. Identify the correct matches -

(1) Environmental (protection) act, 1986 — Protection and quality improvement of air, water

and soil.

(2) Kyota protocol — To mitigate climate change, to reduce green house gases

(3) Montreal protocol — ODS reduction

(4) Chipko movement — Trees protection

(1) A, B (2) A, B, C (3) A, B, D (4) A, B, C, D



10. Which of the following pair(s) is / are correctly matched?

(1) Fossil fuel burning - C02 release

(2) Nuclear plant - Radioactive wastes

(3) CO2- Green house effect

(4) Montreal protocol - Control 03 depletion.

(1) A, B (2) A, B, C (3) A, D (4) A, B, C, D

11. Column I Column II

(I) Arsenic (1) Minamata disease

(II) Nitrate (2) Itai-itai

(III) Mercury (3) Blue-baby syndrome

(IV) Cadmium (4) Skeletal fluorosis

(V) Fluoride (E) Black-foot disease

The correct matching is -

(1) I - B, II- A, III - D, IV - E, V - C (2) I - D, II - A, III - B, IV-C, V - E

(3)l- C, II- B, III-D, IV-A, V - E (4) I - E, II- C, III-A, IV-B, V-D

12. Which of the following is true

(1) Pollution is any undesirable change in physical, chemical or biological characteristic of

air, land, water or soil.

(2) Agents that bring about such an undesirable change are called pollutants

(3) In order to control environmental pollution, the Government of India has passed the

environment (Protection) Act, 1976 to protect and improve the quality of our environmental

(1) A, B, C is correct (2) A and B is correct

(3) B and C is correct (4) A and C is correct

13. Which method is used to control pollutants of particulate nature ?

(1) Combustion (2) Absorption

(3) Electrostatic precipitators (4) Oxidation pond

14. Which of the following figures shows correct relative contribution of greenhouse gases to

global warming?

(1)

(2)

(3)

(4)



15. 'Eco San' toilets are working in many areas of -

(1) Kerala (2) Bihar (3) Assam (4) Mumbai

16. Among the following environmental pollutants which shows biomagnification

(1) SO2 (2) NO3 (3) Hg fungicides (4) O3 & CO2

17. Choose the correct sequence of greenhouse gases with respect to their relative contribution to

global warming in increasing order

(1) N2O, CFC, CH4, CO2 (2) CFC, N2O, CO2, CH4

(3) CH4, N2O, CO2, CFC (4) N2O, CO2, CH4, CFC

18. Choose the odd one out w.r.t. ozone depletion in the stratosphere

(1) UV rays have the ability to both degrade as well as form ozone layer

(2) UV rays are depleting the good ozone in the troposphere

(3) CFCs are disturbing the balance of ozone equilibrium

(4) UV-B rays causes inflammation of cornea called snow blindness

19. Biomagnification refers to increase in concentration of the toxicant at successive trophic

levels, this happens because

(1) A toxic substance accumulated by an organism cannot be metabolized.

(2) A toxic substance accumulated by an organism cannot be excreted.

(3) A toxic substance is passed on to the next higher trophic level.

(4) All of the above.

20. After the conventional sedimentation, filtering and chlorination, lots of dangerous pollutants

still remain. To combat this, the biologists developed a series of six connected marshes and

appropriate plants, algae, fungi and bacteria were seeded into this area, which

(1) Neutralise the pollutants (2) Absorb the pollutants (3) Assimilate the pollutants

(1) All are correct (2) All are wrong

(3) Only (3) is wrong (4) Only (1) is wrong

21. The World Summit on Sustainable development held in 2002 in ________ countries pledged

their commitment to achieve target by 2010.

(1) Rio de Janeiro, 27 (2) Johannesburg (in South Africa), 190

(3) Rio de Janeiro, 190 (4) Johannesburg, 27

22. As the exhaust passes through the catalytic converter

(1) HCs are converted into CO and H2O (2) Nitric oxides are changed to N2 and CO

(3) CO and HCs are removed by oxidation (4) NO and NO2 are converted to CO2 and HCs

23. An international initiative taken in _________ to mitigate climatic changes and to reduce

greenhouse emission is called .

(1) 1987, Montreal Protocol (2) 1997, Kyoto Protocol

(3) 1992, Earth Summit (4) 1985, Vienna Convention



24. The thickness of ozone over poles changes with the season being lowest in

(1) Antarctic spring (2) Polar autumn

(3) Antarctic autumn (4) North hemisphere spring

25. Read the following statements given here below and select the right answer

(1) Kyota protocol, 1997 conference obtained commitments from different countries for

reducing overall greenhouse gas emission at level 5% below 1990 by 2008 – 2012

(2) Montreal protocol was signed in 1987

(3) Montreal protocol became effective in 1989

(4) Montreal protocol was signed to control the emission of ozone depleting substances.

(1) All are correct (2) All are wrong

(3) All are correct except A (4) All are correct except C

26. Amrita Devi Bishnoi Wildlife protection Award is given to the individuals or communities

from

(1) Rural areas (2) Urban areas (3) NGOs (4) None of the above.

27. In collaboration with which one, Ahmad Khan proved that blends of polyblend and bitumen,

when used to lay roads, enhanced the bitumen‘s water repellent properties, and helped to

increase road life by a factor of three.

(1) R. V. College of Engineering (2) The Bangalore City Corporation

(3) Three Mile Island (4) Both a and b

28. Heavy metals defined as elements with density _______ are harmful to ecological systems

(1) > 1 g / cm3 (2) > 2g/cm

3 (3) > 4g / cm

3 (4) >5g/cm

3



ASSERTION & REASON( CLASS WORK)

1. A: Most buses of Delhi were converted to run on CNG by the end of 2002.

R: CNG burns more efficiently than petrol or diesel.

2. A: Domestic sewage primarily contains inorganic matter.

R: BOD is used to measure level of inorganic matter in water.

3. A: Algal bloom is harmful to fishes.

R: Algal bloom does not affect human beings.

4. A: Pollutants and effluents cause accelerated eutrophication.

R: These over stimulate growth of algae.

5. A: A group called FOAM has worked towards environmental health.

R: It helps in preventing deforestation of protected land.

6. A: Landfills do not provide a good solution for waste disposal.

R: Landfills may pollute underground water resources.

7. A: Recycling is the only solution for e-waste.

R: Recycling of e-waste in every country is done without human intervention.

8. A: Green revolution has led to problems of water logging and soil salinity.

R: Irrigation without proper drainage leads to increase in soil salinity.




1. Sheet erosion is caused by: [CPMT 1990]

(1) Wind (2) Heavy rains

(3) Snow (4) Gravity

2. Generally speaking, the atmosphere in big cities is polluted most by: [BHU 1990]

(1) Radioactive fallout (2) Household waste (3) Automobile exhausts (4) Pesticide residues

3. Which major aerosol pollutant is present in jet aircraft emission? [CPMT 1990]

(1) SO2 (2) Fluorocarbons

(3) CCl4 (4) CO

4. Recent reports of acid rains in some industrial cities are due to the effect of atmospheric

pollution by: [CPMT 1991]

(1) Excessive release of NO2 and SO2 by burning of fossil fuels

(2) Excessive release of CO2 by burning of fuels like wood and charcoal, cutting of forests

and increased animal population

(3) Excessive release of NH3 by industrial plants and coal gas

(4) Excessive release of CO in atmosphere by incomplete combustion of coke, charcoal and

other carbonaceous fuels in paucity of oxygen.

5. Domestic wastes contain: [CPMT 1991]

(1) Non-biodegradable pollutants (2) Biodegradable pollutants

(3) Hydrocarbons (4) None of the above

6. The pollution in a city like Delhi may be controlled to a great extent by: [CPMT 1991]

(1) Proper sewage and proper exit of chemicals from factories

(2) Wide roads and factories away from the city

(3) Cleaning city and scanty use of pesticides


7. Lead causes: [CPMT 1992]

(1) Soil pollution (2) Air pollution

(3) Radioactive pollution (4) All of these

8. Checking of re-radiating heat by atmospheric dust, water vapour, ozone, CO2, etc., is known

as:

(1) Greenhouse effect (2) Radioactive effect [MPPMT 1992,94]

(3) Ozone layer effect (4) Solar effect

9. The stratospheric ozone depletion leads to: [AIIMS 1992,97]

(1) Global warming (2) Increase in the incidence of skin cancer

(3) Forest fires (4) Sound pollution

10. Increase in percentage of fauna and decrease in the flora may be dangerous because it

enhances: [DPMT 1992, 96]

(1) Percentage of CO2 (2) Percentage of O2

(3) Percentage of diseases (4) Percentage of radioactive pollution

11. Which is not usually considered an air pollutant? [MPPMT 1993]

(1) CO2 (2) SO2 (3) Hydrocarbons (4) NO2



12. Which does not cause any atmospheric pollution? [MPPMT 1993, 2000]

(1) Hydrogen (2) SO2 (3) CO2 (4) CO

13. Ultra-violet radiation from sunlight causes the reaction that produces: [CBSE 1993]

(1) CO (2) SO2 (3) Ozone (4) Fluorides

14. Pollution can be controlled by: [MPPMT 1993]

(1) Sewage treatment (2) Manufacturing electrically operated vehicles

(3) By checking atomic blasts (4) All of the above

15. Which of the following causes water pollution? [MPPMT 1993]

(1) 2,4-D and pesticides (2) Smoke

(3) Automobile exhaust (4) Aeroplanes

16. Ozone layer is destroyed by: [CPMT 1993]

(1) More release of CO2 (2) More release of O2 (3) Uses of coal (4) Chlorofluorocarbons

17. Air pollution is not caused by: [CPMT 1993]

(1) Pollen grains (2) Automobiles (3) Industries (4) Hydro-electric power

18. The gas causing maximum destruction of ozone is:

(1) CFC (2) Liquid NH3

(3) SO2 (4) CO

19. Ozone layer in stratosphere is affected by: [CPMT 1993]

(1) Excess CO2 (2) Excess CO (3) Chlorofluorocarbon (4) Low rainfall

20. Which of the following is a major green-house gas? [CBSE 1994]

(1) CO2 (2) Freon

(3) CFC (4) None of these

21. Taj Mahal is threatened due to the presence of: [CBSE 1995]

(1) Chlorine (2) SO2

(3) Oxygen (4) Hydrocarbons

22. When excess of sewage is dumped in the river, it‘s BOD: [CBSE 1995]

(1) Increases (2) Slightly decreases

(3) Remains unchanged (4) Decreases drastically

23. Which of the following isotopes is most dangerous to Homo sapiens? [CBSE 1995]

(1) Phosphorus-32 (2) Strontium-90

(3) Cesium-137 (4) Iodine-131

24. "Catalytic converter" is used in automobiles: [AIIMS 1995]

(1) For removing the poisonous lead

(2) For converting CO and harmful hydrocarbons into CO2 and water vapours

(3) For removing water

(4) None of the above

25. The worst environmental hazards created accidents in nuclear power plant and MIC gas

tragedy respectively in: [CBSE 1996; BHU 2000]

(1) Russia in 1990 and Bhopal in 1996 (2) Ukrain in 1986 and Bhopal in 1984

(3) Bhopal in 1994 and Russia in 1990 (4) Ukrain in 1988 and USA in 1984



26. Air pollution effects are usually found on: [MPPMT 1997]

(1) Leaves (2) Flowers (3) Stems (4) Roots

27. Water pollution : [MPPMT 1997]

(1) Increases oxygenation (2) Decreases turbidity

(3) Increases turbidity and deoxygenation (4) Increases photosynthesis

28. Oxides of sulphur and nitrogen are important pollutants of: [MPPMT 1997]

(1) Air and Water (2) Air

(3) Water (4) Soil

29. The population of a place or an area tends to increase when: [AMU 1997]

(1) Predation increases (2) Emigration occurs

(3) Immigration occurs (4) Reproductivity decreases

30. Green house effect is due to increasing concentration of [MPPMT 2001]

(1) CO2 (2) CO (3) SO2 (4) O3

31. Which are indices of atmospheric purity (IAP)? [BCECE (P.T.Exam.) 2001]

(1) Ferns (2) Algae

(3) Fungi (4) Lichens

32. SO2 affects: [BCECE (P.T.Exam) 2001]

(1) Nuclear membrane (2) Cell wall (3) Mitochondria (4) All membrane systems

33. 'Greenhouse effect' is due to: [CPMT 2001]

(1) Depletion of O3 layer and increase in CO2 concentration

(2) Depletion of CO2 layer and increase in O3 concentration

(3) Depletion of O3 layer and decrease in CO2 concentration

(4) Afforestation

34. Presence of E.coli in water indicates : [CPMT 2001]

(1) Soil pollution (2) Sewage pollution (3) Industrial pollution (4) All of these

35. Reason of lung cancer is: [CBSE 2001]

(1) Coal mining (2) Calcium fluoride (3) Cement factory (4) Bauxite mining

36. What is the intensity of sound in normal conversation? [CBSE 2001]

(1) 10-20 decibels (2) 30-60 decibels (3) 70-90 decibels (4) 120-150 decibels

37. The result of ozone hole is: [CET Karnataka 2001]

(1) Global warming (2) Acid rain

(3) Greenhouse effect (4) The UV radiations reach the earth

38. Biological oxygen demand is: [Manipal 2001]

(1) Amount of O2 required by microbes to decompose organic waste

(2) Amount of O2 produced by microbes on decomposing organic waste

(3) Amount of O2 required by microbes to survive

(4) None of the above



39. Which of the following is renewable resource? [Manipal 2001]

(1) Solar energy (2) Air

(3) Petroleum (4) Water

40. Ozone hole is accelerated due to release of: [Manipal 2001]

(1) CO2 (2) CFCs (3) O2 (4) SO2

41. DDT is a [BCECE 2002]

(1) Biodegradable pollutant (2) Non-biodegradable pollutant

(3) Antibiotic (4) None of these

42. Acid rains contain: [AFMC 2002]

(1) SO2, NO2 (2) NO3

(3) O3 (4) CO

43. Minamata disease in Japan was caused by pollution of water by :

[Uttaranchal PMT 2001; BCECE 2002]

(1) Lead (2) Cyanide

(3) Mercury (4) Methyl isocyanate

44. Which of the following is a 2° (secondary) pollutant? [Kerala PMT 2002]

(1) PAN (2) SO3

(3) SO2 (4) H2S

45. Acid rain is due to increase in atmospheric concentration of : [MPPMT 2002]

(1) Ozone and dust (2) CO2 and CO

(3) SO3 and CO (4) SO2 and NO2

46. B.O.D. is connected with: [MPPMT 2002]

(1) Organic matter (2) Microbes

(3) Both (1) and (2) (4) None of these

47. SO2 pollution is indicated by: [MPPMT 2002]

(1) Grasses (2) Mosses

(3) Lichens (4) Fossils

48. Maximum greenhouse gas is released by which country ? [CBSE 2002]

(1) India (2) France

(3) USA (4) Britain

49. Green muffler is used against which type of pollution? [AIIMS 2002]

(1) Air (2) Water

(3) Soil (4) Noise

50. Acid rain will not affect: [BCECE 2002]

(1) Plants (2) Lithosphere

(3) Animals (4) Ozone layer

51. Which of the following gases contributes to global warming ? [CET Karnataka 2002]

(1) Nitrogen dioxide (2) Carbon dioxide

(3) Sulphur dioxide (4) Carbon monoxide

52. Which one of the following pairs is mismatched ? [CBSE 2005]

(1) Biomass burning - release of CO2 (2) Solar energy - greenhouse effect

(3) Fossil fuel burning - release of CO2 (4) Nuclear power - radioactive wastes



53. Which of the following is not used for disinfection of drinking water ? [CBSE 2005]

(1) Chlorine (2) Chloramine

(3) Phenyl (4) Ozone

54. Formation of non-functional methaemoglobin causes blue baby syndrome. This is due to

(1) Excess of arsenic concentration in drinking water [AIIMS 2005]

(2) Excess of nitrates in drinking water

(3) Deficiency of iron in food

(4) Increased methane content in the atmosphere

55. Which one of the following statements pertaining to pollutants is correct? [AIIMS 2005]

(1) DDT is a non-biodegradable pollutant

(2) Excess fluoride in drinking water causes osteoporosis

(3) Excess cadmium in drinking water causes black foot disease

(4) Methylmercury in water may cause "Itai Itai" disease

56. Which one of the following is an environment-related disorder with the correct main cause?

(1) Black lung disease (pneumoconiosis) found mainly in workers in stone quarries and

crushers

(2) Blue baby disease (methaemoglo-binaemia) due to heavy use of nitrogenous fertilizers in

the area

(3) Non-Hodgkin's Lymphoma found mainly in workers involved in manufacture of neem

based pesticides

(4) Skin cancer mainly in people exposed to benzene and methane [AIIMS 2006]

57. The Montreal Protocol is related to: [AIIMS 2006]

(1) Persistent Organic Pollutants

(2) Global warming and climate change

(3) Substances that deplete the ozone layer

(4) Biosafety of Genetically Modified Organisms

58. Montreal Protocol which calls for appropriate action to protect the ozone layer from human

activities was passed in the year [CBSE 2006]

(1) 1985 (2) 1986

(3) 1987 (4) 1988

59. Photochemical smog pollution does not contain [CBSE 2006]

(1) PAN (peroxyacyl nitrate) (2) Ozone

(3) Nitrogen dioxide (4) Carbon dioxide

60. When domestic sewage mixes with river water : [AIPMT (Mains) 2010]

(1) The increased microbial activity uses up dissolved oxygen

(2) The river water is still suitable for drinking as impurities are only about 0.1%

(3) Small animals like rats will die after drinking river water

(4) The increased microbial activity releases micro nutrients such as iron

61. Appropriate measures to reduce overall greenhouse gas emission are the commitments of the

(1) Montreal Protocol (2) Environment Act

(3) Kyoto Protocol (4) Earth Summit [DPMT 2010]

62. Which one of the following pairs of gases are the major cause of ―Greenhouse effect‖?

(1) CO2 and CO (2) CFCs and SO2 [AIPMT 2011]

(3) CO2 and N2O (4) CO2 and O3



63. Secondary sewage treatment is mainly a

(1) Mechanical process (2) Chemical process [AIPMT 2011]

(3) Biological process (4) Physical process

64. Which of the following statements is wrong in case Bhopal gas tragedy? [AIPMT 2011]

(1) Thousands of human being died (2) Radioactive fall out engulfed Bhopal

(3) It took place in the night of December 2/3, 1984

(4) Methyl isocyanate gas leakage took place

65. Eutrophication is often seen in [AIPMT 2011]

(1) Fresh water lakes (2) Ocean

(3) Mountains (4) Deserts

66. At present, the concentration of CO2 in the atmosphere is about

(1) 100 ppm (2) 240 ppm [DUMET 2011]

(3) 380 ppm (4) 520 ppm

67. The main cause of pollution in metro cities is

(1) Burning of fossil fuel (2) Water plants [UP CPMT 2011]

(3) Domestic products (4) None of these

68. Acid rain is due to

(1) CO2 and H2O (2) CO and NO2 [OJEE 2011]

(3) SO2 and NO2 (4) SO2 and N2O

69. Term used for accumulation of non-degradable pollutant in higher trophic level is

(1) Biomagnification (2) Eutrophication [OJEE 2011]

(3) Biome (4) Ecotone

70. Cigarette smoking causes

(1) Skin cancer (2) Blood cancer [OJEE 2011]

(3) Bone cancer (4) Lung cancer

71. Minamata was detected in

(1) Japan (2) Australia [OJEE 2011]

(3) India (4) China

72. Which one of the following is mainly responsible for green house effect?

(1) SO2 (2) CO2 [WB JEE 2011]

(3) CO (4) O2

73. Match the items of column I with column II and choose the correct answer.

[Kerala CEE 2011]

Column I Column II

A. Electrostatic precipitator 1. Removes gases like SO2

B. Scrubber 2. Reduces automobile emission

C. Catalytic converter 3. Removes particulate matter A B C (1) 2 3 1 (2) 3 2 1 (3) 1 2 3 (4) 3 1 2



74. Which one of the following is a correct, option with reference to pathogenic bacteria and

DDT? [Guj CET 2011]

(1) Bacteria can undergo multiplication and DDT is degraded by living cells.

(2) Bacteria can be degraded by living cells and DDT cannot be degraded by living cells.

(3) Bacteria can undergo biological magnification and DDT can be degraded by living cells.

(4) Bacteria can undergo biological magnification and DDT cannot be degraded by living

cells.

75. Which one of the following is a wrong statement? [AIPMT 2012]

(1) Most of the forests have been lost in tropical areas.

(2) Ozone in upper part of atmosphere is harmful to animals.

(3) Greenhouse effect is a natural phenomenon.

(4) Eutrophication is a natural phenomenon in freshwater bodies.

76. Measuring biochemical Oxygen Demand (BOD) is method used for [AIPMT 2012]

(1) Estimating the amount of organic matter in sewage water.

(2) Working out the efficiency of oil driven automobile engines.

(3) Measuring the activity of Saccharomyces cerevisae in producing curd on a commercial

scale.

(4) Working out the efficiency of RBCs about their capacity to carry oxygen.

77. The domestic sewage in large cities [AIPMT 2012]

(1) has a high BOD as it contains both aerobic and anaerobic bacteria.

(2) is processed by aerobic and then anaerobic bacteria in the secondary treatment in Sewage

Treatment Plants (STPs)

(3) when treated in STPs does not really require the aeration step as the sewage contains

adequate oxygen.

(4) has very high amount of suspended solids and dissolved salts.

78. DDT residues are rapidly passed through food chain causing biomagnification because DDT

is

(1) Liposoluble (2) Moderately toxic [UP CPMT 2012]

(3) Non- toxic to aquatic animals (4) Water soluble

79. The Air Prevention and Control of Pollution Act came into force in:

(1) 1990 (2) 1975 [NEET 2013]

(3) 1981 (4) 1985.

80 Global warming can be controlled by: [NEET 2013]

(1) Increasing deforestation, reducing efficiency of energy usage.

(2) Reducing deforestation, cutting down use of fossil fuel

(3) Reducing reforestation, increasing the use of fossil fuel

(4) Increasing deforestation, slowing down the growth of human population.

81 A scrubber in the exhaust of a chemical industrial plant removes: (AIPMT 2014)

(1) gases like ozone and methane

(2) particulate matter of the size 2.5 micrometer or less

(3) gases like sulphur dioxide

(4) particulate matter of the size 5 micrometer or above

82 A location with luxuriant growth of lichens on the trees indicates that the: (AIPMT 2014)

(1) location is highly polluted (2) location is not polluted

(3) trees are very healthy (4) trees are heavily infested



83. The UN Conference of Parties on climate change in the year 2011 was held in: (AIPMT 2015)

(1) South Africa (2) Peru (3) Qatar (4) Poland

84. Rachel Carson's famous book "Silent Spring" is related to: (AIPMT 2015)

(1) Noise pollution (2) Population explosion

(3) Ecosystem management (4) Pesticide pollution

85. Which of the following is not one of the prime health risks associated with greater UV

radiation through the atmosphere due to depletion of stratospheric ozone? (AIPMT 2015)

(1) Reduced Immune System (2) Damage to eyes

(3) Increased liver cancer (4) Increased skin cancer

86. Joint forest management was introduced in India during (NEET 2016-I)

(1) 1960s (2) 1970s

(3) 1980s (4) 1990s

87. Depletion of which gas in the atmosphere can lead to an increased incidence of skin cancers

(1) Nitrous oxide (2) Ozone

(3) Ammonia (4) Methane (NEET 2016-I)

88. A lake which is rich in organic waste may result in

(1) increased population of fish due to lots of nutrients

(2) mortality of fish due to lack of oxygen

(3) increased population of aquatic organisms (NEET 2016-II)

(4) drying of lake due to algal bloom

89. The highest DDT concentration in aquatic food chain shall occur in

(1) crab

(2) eel

(3) phytoplankton (NEET 2016-II)

(4) seagull

90. Biological Oxygen Demand (BOD) may not be a good index for pollution of water bodies

receiving effluents from

(1) dairy industry

(2) petroleum industry

(3) sugar industry (NEET 2016-II)

(4) domestic sewage



EXERCISE (KEY) LEVEL–I (CLASS WORK)

1. (1)

2. (4)

3. (1)

4. (1)

5. (1)

6. (1)

7. (4)

8. (2)

9. (1)

10. (3)

11. (2)

12. (2)

13. (1)

14. (2)

15. (3)

16. (1)

17. (1)

18. (1)

19. (1)

20. (3)

21. (3)

22. (3)

23. (1)

24. (2)


1. (3)

2. (2)

3. (3)

4. (3)

5. (4)

6. (3)

7. (2)

8. (4)

9. (4)

10. (4)

11. (4)

12. (2)

13. (3)

14. (1)

15. (1)

16. (3)

17. (1)

18. (2)

19. (4)

20. (1)

21. (2)

22. (3)

23. (2)

24. (1)

25. (1)

26. (1)

27. (4)

28. (4)

ASSERTION & REASON (CLASS WORK)

1. (1) 2. (4) 3. (3) 4. (1) 5. (3) 6. (1) 7. (3) 8. (1)

PREVIOUS YEAR’S QUESTIONS (HOME WORK)

1. (2)

2. (3)

3. (2)

4. (1)

5. (2)

6. (4)

7. (1)

8. (1)

9. (2)

10. (1)

11. (1)

12. (1)

13. (3)

14. (4)

15. (1)

16. (4)

17. (4)

18. (1)

19. (3)

20. (1)

21. (2)

22. (1)

23. (2)

24. (2)

25. (2)

26. (1)

27. (3)

28. (2)

29. (3)

30. (1)

31. (4)

32. (4)

33. (1)

34. (2)

35. (3)

36. (2)

37. (4)

38. (1)

39. (4)

40. (2)

41. (2)

42. (1)

43. (3)

44. (1)

45. (4)

46. (3)

47. (3)

48. (3)

49. (4)

50. (4)

51. (2)

52. (2)

53. (3)

54. (2)

55. (1)

56. (2)

57. (3)

58. (3)

59. (4)

60. (1)

61. (3)

62. (3)

63. (3)

64. (2)

65. (1)

66. (3)

67. (1)

68. (3)

69. (1)

70. (4)

71. (1)

72. (2)

73. (4)

74. (2)

75. (2)

76. (1)

77. (1)

78. (1)

79. (3)

80. (2)

81. (3)

82. (2)

83. (1)

84. (4)

85. (3)

86. (3)

87. (2)

88. (2)

89. (4)

90. (2)

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MODULE V - panacea.iitianspace.com

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