Bio1.EcosystemsU

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keepit simplescience

Preliminary Biology Topic 1 Ecosystemscopyr ight 2005-2008 keep it simple sciencewww.keepitsimplescience.com.au

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Preliminary Biology Topic 1

A LOCAL ECOSYSTEM

What is this topic about?To keep it as simple as possible, (K.I.S.S.) this topic involves:1. DISTRIBUTION & ABUNDANCE OF ORGANISMS

2. BIOTIC & ABIOTIC FACTORS

3. ROLES & RELATIONSHIPS

4. THE FLOW OF ENERGY & MATTER

5. ADAPTATIONS TO ENVIRONMENT

6. HUMAN IMPACTS

but first, some definitions...

Ecologyis the study of living things and their environment,and all the inter-relationships between the life-forms and the factors of the environment itself.

EcosystemAn ecosystem comprises all the l iving things andthe non-living environment of a particular, definedarea. The size of an ecosystem can varyenormously... you might study the ecologyunder one rock, or in a lake. You might consider anentire mountain range as one ecosystem, or anentire ocean. Ultimately, the entire Earth can beconsidered as a single ecosystem.

Communityrefers to all the living things within an ecosystem...all the different types and individual organisms.

Populationrefers to all the individuals of a particular species

living within the ecosystem. The community withina complex ecosystem such as a coral reef, or atropical rainforest, contains thousands ofpopulations of different species.

ANAUSTRALIAN ECOSYSTEMsun

THESUNPROVIDESALLTHE ENERGY FORTHE ECOSYSTEM

Thetemperature,amountoflight,theair,waterandthesoilarevitalnon-livingfactors ofeveryecosystemTheplantsandanimalsinteractwitheachother,andwiththenon-livingenvironment


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Quadrats&

Capture-Recapture

TransectStudies

Abiotic

FactorsBiotic

Factors

Parasite

&Host

Predator&

Prey

Commensalism

Competition

Mutualism

Al lelopathy

Cycling of

matter.

Flow of Energy

Food

Chains

Food

Webs

Biomass

PyramidsStructural

Physiological

BehaviouralLoss of Habitat

PollutionEutrophicationAl ien Species

A LOCAL

ECOSYSTEM

Distribution&

Abundance

Factors ofan Ecosystem

Roles

&

Relationships

Flow of

Energy & MatterAdaptations

to

EnvironmentHumanImpacts

CONCEPT DIAGRAM ( Mind Map ) OF TOPICSome students find that memorising the OUTLINE of a topic helps them learn and remember

the concepts and important facts. As you proceed through the topic,come back to this page regularly to see how each bit fits the whole.

At the end of the notes you wil l find a blank version of th is Mind Map to pract ise on.


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Distribution

In ecology, distribution refers to wherewithin an ecosysytem the individuals of aspecies are located.

Some species might be more or lessevenly distributed throughout the areabeing studied, but often the population ofa species is clumped together, or foundonly in certain parts of the environment.

How a species is distributed gives cluesabout how it is interacting with theenvironment.

For example:

So, one of the first things to do whenstudying an ecosystem is to study thedistribution of the organisms present. Onegood way to do this is by carrying out aTransect Study.

An animal that isusually found in treetops may be there to

find itsfood, ormay be

escapingits

enemies.

PreliminaryBiologyTopic1copyright2005-2008 keepitsimplesciencewww.keepitsimplescience.com.au


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1. DISTRIBUTION & ABUNDANCE OF ORGANISMS

A plant found mainly along the banksof creeks or rivers may have a

greater need for water to grow, ormight only be able to reproduce by

spreading its seeds in water.

You may have done a Transect Study as partof your practical work, or field trip.

For schools near the coast, a common f ieldtrip is to study the rocky seashore

environment.

The first questions you might ask when beginning to study any ecosystem are: which organisms live here? where do they live, exactly?

how many of them are there?

Transect Study

A Transect is like a cross-sectionthrough a study area.

The idea is to define a line which cuts rightacross the area being studied. This couldbe a string line or a series of marker stickshammered into the soil.

The study is done by moving along the lineand noting and recording which speciesare located at each point.

Often plants are the main subjects of aTransect Study, because many animalsmove around so far and so quickly thatthey cant be studied this way.

ATypicalRockySeashoreThephotoshowshorizontalstripesoflivingthings.Eachstripeisapopulationofseaweeds,orbarnacles,ortube-worms,etc.Whystripes?turnover...


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In sea-shore studies it is quicklydiscovered that the different organismstend to be found in quite distinct zones which are related to the vertical

heights above and below the tide levels.TRANSECT DIAGRAM OF A ROCKY SEASHORE

High Tide level

Blue periwinkles

Neptunes necklace seaweed

Low Tide level

30 metres

3metres

Note: Vertical scale is exaggerated

Crabscommon

Black & striped periwinklescommon here

Brown bubble weed

Sea Urchins & Starfish

common here

Kelp seaweed only foundat lower levels

Distribution at a Rocky SeashoreExactly where each species is found isan indication of the interactions in theecosystem between each species andfactors such as:

Food Supplies they need to be near.

Predators they need to avoid.

Wave Action. Most of the organismsalong the sea-shore are well adapted towithstand the pounding of waves, butsome are better adapted than others.

Exposure to AirSea-shore animals are all sea creatureswhich can withstand being exposed fora while at low tide. How well they copewith this often determines their exactdistribution.

AbundanceAbundance refers to how many individuals are in the population

of a species in the ecosystem.

In some cases it can be easy enough to countthe population directly.

For example, to find the abundance of largetrees in a small forest, simply walk back-and-forth in a grid pattern and count as you go.

However, small organisms, large areas and animalsthat hide or move around a lot make direct countingimpossible. In many cases, abundance of a speciesmust be done by sampling... studying smallsamples of the environment, then scaling the dataup to the whole area.

Two commonly used sampling techniques

are described on the next page.

Itwouldbeimpracticaltotrytocountallthebarnaclesonaseashore.Samplingthepopulationismuchfaster.


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Quadrat SamplingA quadrat is a simple wire/wooden/plasticframe which is dropped onto the ground atrandom throughout the study area.

At each quadrat drop the number of the

species of interest is counted. After a numberof drops (the more, the better) the averagenumber of organisms per quadrat iscalculated.

Finally, the estimated population is found byscaling-up from the area of the quadrat tothe total area being studied.

EXAMPLE OF AQUADRAT STUDYKEY:

Plantstudied

Quadrat

drops

8 metres

8metres

StudyArea

= 8x8= 64 m2

1 m2

In the example shown, the quadrat has been dropped 8 times.The numbers of plants in each quadrat drop were 2,1,0,3,1,1,1,1

This gives an average of 1.25 plants in each quadrat.

Estimated = Average count x Study areaPopulation per quadrat Quadrat area

Estimated = 1.25 x 64 = 80 plantsPopulation 1

Remember this is anestimate only, and

can be improved byincreasing the

number of drops .

LimitationsThis technique relies on the tagged individuals mixing randomly

back into the population and being re-caught again at random.

Sometimes this doesnt happen.

For example, intelligent mammals learn to avoid the traps or nets, or may even enjoy being caught (for thefood in a trap) and learn to seek out the traps. Either way, this makes the estimate inaccurate.

1. Capture a numberof the species being

studied.

Example:1st Capture is50 individuals

2. Mark or tagthe animals

3. Release animals backwhere they were

captured.

4. Carry out a secondcapture program.

Example:2nd Capture is60 individuals(not all shown)

5. Count how many of the2nd capture are markedfrom the 1st capture.

Example:Out of 60 in the 2nd capture, 3 are marked. So,5% (1/20) of the 2nd capture are re-captures.

wait.

..

Capture-Recapture SamplingThe obvious problem with the Quadrat method is

that it does not work with animals that will run, fly,

or swim away from you.

For mobile animals, or secretive, hard-to-find

types, the capture-recapture technique can be

useful.

For the example shown, 5% (1/20) of the 2nd

capture are re-captures. So statistically, the 1st

capture sample of 50 should represent 1/20 of the

total population of the study area.

Therefore, population estimate = 1,000 individuals.(50 x 20)

Mathematically,

Estimated = 1st capture x 2nd capturePopulation no.marked in 2nd capture(no. re-captured)

= 50 x 603

= 1,000 individuals


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Worksheet 1

Distribution & AbundanceFill in the blank spaces.

Distr ibut ion in ecology refers to a).....................

a species is located in an area. This gives clues

to how a species is b)............................................with the environment. For example, an animal

found predominantly in treetops might be there

to find c)........................, or it may be

d)............................ from its enemies.

A good technique for studying distribution is

carry out a e).......................................... study.

This is where you work along a

f)..................................... across the study area,

noting g)................... ........................ .......................

at each point.

h)...................................... refers to how many

individuals of a species are in an environment.

One way to estimate this is by dropping

i).................................... at random throughout the

area.

At each drop you count how many organisms are

in the quadrat. At the end you calculate the

j)............................... per quadrat.

Knowing the area of each quadrat, and the area of

k)................................................., the total population

can be estimated. The accuracy will be improvedby l).........................................................

.......................................

For animals that move around a lot, the abundance

is best estimated by the m).....................................

.................... method. This involves capturing a

sample of the population, then n).............................

them in some way, and then o).....................................

them again.

Later, you carry out a second p)...............................,

and count how many of the sample are

q)................................... This allows calculation of an

estimate of the r)..................................... One

limitation of this technique is that it relies on the

captured specimens s).............................................

.............................., which doesnt always happen.

Worksheet 2 Calculating Abundance

Quadrat Study Problems1.

Abundance of starfish on a rock platform wasstudied by the quadrat method. The quadrat was

a plastic frame with an area of 0.25 m2.

The rock platform was a rectangle

approximately 20m x 30m.

The numbers of starfish in 10 quadrat drops

were: 8, 0, 14, 11, 3, 1, 0, 0, 7, 2.

Estimate the starfish population on the rock

platform.

2.

A farmer wished to est imate the populat ion

abundance of a noxious weed species in a

paddock measuring 300 x 400 metres. He used a

rectangular wire quadrat frame 1.0 x 0.5 metre.

The number of target weeds in 20 quadrat

drops were: 2, 8, 0, 15, 11, 0, 2, 1, 0, 9, 16, 3, 7,

13, 0, 1, 7, 0, 8, 2.

What is the approximate population of weeds in

the paddock?

Capture-Recapture Problems3.

A capture-recapture study was carried out onthe lizard population on an island. In the first

capture exercise, 230 lizards were captured,

tagged and released.

A week later, 156 lizards were captured. Of these,

18 had tags from the 1st capture.

Calculate an estimate of the lizard population on

the island, to the nearest thousand.

4.

To estimate the possum population in area, 65

possums were captured unharmed, tagged and

released. A week later 48 possums were

captured. Of these, 12 had tags.

Estimate the possum population.

It was later found that the possums rather

enjoyed being trapped because of the tasty food

used as bait. Does this mean your population

estimate may be too high or too low?

Explain your answer.


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Worksheet 3 Practice Questions (Section 1)

Multiple Choice1. When studying an ecosystem, a transect study

could be useful for recording the:

A. abundance of species within the study area.

B. distribution of species within the area.

C. special adaptations of species to the habitat.

D. food chains in the area.

2.

It would be reasonable to infer from this transect study

that:

A. Blue Periwinkles eat kelp plants.

B. blue periwinkles can withstand drying effects

at low tide better than starfish can.

C. Crabs can survive the effects of wave actionbetter than bubble weed.

D. Kelp has special adaptations to resist drying.

3. The best way to improve the accuracy and reliability

of a quadrat study is to:

A. use a bigger quadrat frame.

B. deliberately drop quadrats where the target

species is found in larger numbers.

C. measure the size of the study area more

carefully.

D. make more quadrat drops.

4. When using the capture-recapture technique,

which of the following would be most likely to result in

an INACCURATE estimate of population size.

A. The marking technique used reduces survival

chances of the animals.

B. Increasing the number captured in the 2nd

capture operation.

C. After release from the first cature, the animals mix

randomly back into the population.

D. Increasing the number captured in the first

capture operation.

Longer Response QuestionsMark values given are suggestions only, and are to

give you an idea of how detailed an answer is

appropriate.

5. (4 marks)

The following is a students sketch diagram of a

transect done to study the distribution of 4 plant

species J, K, L and M in a certain area.

Describe the distribution of species K and L.

6. (3 marks)Using a capture-recapture method to estimatethe population of trout fish in a lake, the followingresults were obtained:

1st capture: 537 trout tagged & released.2nd capture: 832 captured.Of these 45 were tagged.

To the nearest 1,000, how many trout are in thelake? Show your working or reasoning.

7. (6 marks)To estimate the population size for a small plantspecies living in a field, a quadrat study wascarried out. The field was rectangular, measuring120m x 85m.

The quadrat used was a square wired frame0.50m x 0.50m = 0.25 m2 area.It was dropped at random 10 times in the field. The

count of the target species in each of the dropswas:- 8, 14, 2, 5, 9, 22, 3, 0, 12 and 7.

a) Calculatei) the area of the field.ii) the average number of plants per quadrat.

b) Find an estimate of the size of the plantpopulation in the field. Show working.

c) Suggest one way to improve this study to give amore accurate estimate.

TRANSECT DIAGRAM OF A ROCKY SEASHORE

High Tide level

Blue periwinkles

Neptunes necklace seaweed

Low Tide level

Crabscommon

Black & striped periwinklescommon here

Brown bubble weed

Sea Urchins & Starfishcommon here

Kelp seaweed only foundat lower levels

Pond

CreekKey

JK L M

Verticalscale

exaggerated


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2. BIOTIC & ABIOTIC FACTORS OF AN ECOSYSTEM

Viscosityis a measure of the stickiness of asubstance, and how easy or difficult it isto move through it. On land, plants andanimals are surrounded by air, whichhas very low viscosity and is easy tomove through.

Water has a much higher viscosity and ismore difficult to move through. As aresult, many aquatic animals arestreamlined, and equipped with powerfultails for propulsion.

Availability of Gases(oxygen & carbon dioxide)

Since the air is about 20% oxygen, it is readily available in terrestrial environments.Carbon dioxide (needed by plants for photosynthesis) is only 0.04% of air,

so land plants are limited by this.

These gases do NOT dissolve well in water, so the concentration of gasesin aquatic environments is very low, and gets lower as the water gets warmer.

For this reason, fishs gills have to be highly efficient to extract the

necessary oxygen, and are far better than our lungs for gas exchange.

Biotic Factors

( biotic = living)examples...

Food organismsPredators

Disease organismsCompetitors

Abiot ic Factors

(non-living)

Availabi li ty of waterAvailabi lity of oxygen

Light intensityTemperature rangeSoil characteristics

...and many more.

STREAMLINING

Most of body is muscleto power the tail

The distribution and abundance of any species within an ecosystemdepends on a whole host of factors...

Comparison of Abiot ic Characteristics in theTerrestrial Environment (on land) & Aquatic Environment (in water)

Buoyancyis a measure of flotation ability. Wateris very buoyant and supports plant andanimal bodies against the pull of gravity.Aquatic organisms do not need st rongstems or legs to hold themselves up.

Terrestrial plants need strong stems ortrunks of wood to grow upwardsagainst gravity. Animals need strongskeletons.

Strongtrunk to

hold leavesup to catch

light

Bony skeletonsupports bodyagainst gravity


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Availability of Water

Terrestrial environments are subject toevaporation, and plants and animals musthave ways to conserve water, by havingwater-proof skin, or avoiding losses during

excretion. This problem becomes extremein some environments such as deserts.

For sea-living plants and animals likejellyfish and worms, water is never aproblem. They are constantly surroundedby a liquid exactly the same as their bodyfluids. They do not need to have specialmechanisms to collect or conserve water.

However, in some cases the organisms are

surrounded by water, but they have waterproblems due to osmosis. This will bestudied in the next topic, but in summary:

In salt-water environments fish lose waterby osmosis (mainly from their gills) andmust constantly replace it.

In fresh water, osmosis causes water toflow into the organisms body and mustconstantly be pumped out again. Theirkidneys are mainly used to excrete water,

rather than body wastes.

SALTWATER FRESH WATERFISH FISH

Must drinkconstantly to

replace water loss

Osmosis suckswater from body.

Mustexcretewater

constantly

Absorbs water due toosmosis

Temperature Variation

On land the temperature can easily vary20oC from day to night, and even more fromsummer to winter. Living things must beable to cope with that while maintaining

stable internal body temperatures.

Terrestrial animals need fur or feathers forinsulation, or have physiological responsessuch as sweating or shivering. Somechange their behaviour (sunbaking orseeking shade) in order to cope.

Water-living organisms generally do not

need such special adaptations becauseaquatic environments have very stabletemperatures.

However, water-living mammals are oftenheavily insulated by blubber (fat) tomaintain their high body temperature incold water.

Thisseallooksfatbecausesheis!Thicklayersofblubberarebothfoodstorageandvitalinsulationtoconservebodyheatincold water.

Dogskeepcoolbypantingwhentheygettoohot.Theyhavefewsweatglands,butpantingevaporateswaterfromgumsandtongue.Thishasacoolingeffect.

Conservingwateriscriticalforsurvivalinadesertenvironment


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Availabil it y of LightLight is essential for plants to carry out

photosynthesis. This process makes all the

food, so the availability of ligh t is a critical factor

in any ecosystem.

Light penetrates through air very easily, so most

terrestrial environments get plenty of light forthe plants. The floor of a rainforest is an

exception... here the dense canopy of trees

means very little light penetrates to reach the

smaller species or seedlings.

Rainforest plants have adapted to this in many

ways:

Epiphytes (e.g. staghorn ferns) germinate and

grow high up in other plants and so avoid the

darkness below.

Plants li ving on the rainforest floor have large,

broad leaves, packed with extra chorophyll, to

absorb what little light is available.

In contrast to air, water does NOT allow light

through so easily. Light can penetrate the

surface layers easily enough, but even just 10

metres deep, much of the light has been

absorbed, and by 100 m down it is totally dark.

Also, water does not absorb all the di fferent

colours (wavelengths) equally. Red and orangeare absorbed rapidly, while green and blue

penetrate deeper into the water.

Most

seaweeds

are not the

familiar

green of land

plants. Many

are brown or

red because

they contain

special

pigments to

absorb thedominant

blue

wavelength

of light they

receive.

In deep ocean waters there is no light and

consequently no plants. Deep ecosystems rely

on dead organic remains drifting down from

above for their food supply. On the deep ocean

floor, some ecosystems are based on food made

by chemosynthesis around volcanic vents. This

will be explained in a later topic.

Blue light penetratesto greater depth

Red light isabsorbed near

the surface

Manyseaweedshavespecialpigmentstoefficientlyabsorbtheavailablelight.

Differentcolours(frequencies)oflightpenetratewatertodifferentdepths.

Birdnestfernepiphyteinarainforesttree

BrownKelpSeaweed


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Worksheet 4Biotic & Abiot ic Factors

Divide these ecosystem factors into 2lists... the Biotic and Abioticfactors.

Light, prey, diseases, oxygen, water,predators, soil, temperature, foodplants, exposure, competitors, acidity.

Fill in the blanks

In comparing the a)...................................(on land) environment with theb)...................................... (in water)

environment, a number of Abioticfactors are very important;

c).................................. refers to howeasy/difficult it is to move through themedium. Air has a very d)......................................... while water is muche).......................................... Because ofthis, aquatic animals often have af).............................. shape.

Buoyancy is a measure ofg).................................. ability. Water ismuch h)....................... (more/less)buoyant than air. Terrestrial animalsand plants need strongi)............................... structures towithstand gravity, while aquaticorganisms are supported by the water.

Comparing temperature variations, the

terrestrial environment showsj)..................................... var iation thanwater. Thats why many land animalshave special features such ask)................................ for insulation, orthe ability to l)...................................when too hot.

Important gases like m)..........................are abundant in the air Gases do notn).............................. very well in water,so aquatic animals need very efficiento)................................. or other breathingorgans.

On land, plants and animals must haveways to p)...............................................water and avoid dehydration. This couldinvolve having q).......................................skin, or avoiding excessive water lossduring r).................................... Inaquatic environments there can be

water problems too, due to the processof s)......................................................For example, salt-water fish constantlyt)....................................... water, whilefresh-water fish need to constantlyu).............................. water.

On land, availability of light is generallynot a problem, except in environmentssuch v).......................................... Tocope with this, epiphyte plants such as

w)................................, grow up in thetops of trees. Plants on the floor mayhave leaves which arex)........................................................... toabsorb any light available.

In water, light penetration is poor, andthe different y)........................................of light penetrate differently.z)........................ wavelengths are

absorbed rapidly, whileaa)............................... penetrates further.Seaweed plants often have specialab)................................ (often red/brownin co lour) to better absorb the availablelight. In the very deep ocean there is nolight, and no ac)......................................can survive there. Ecosystems mustrely on ad)................................. driftingdown from above, for food, or onae)............................ around volcanic

vents.

WHENCOMPLETED,WORKSHEETSBECOMESECTIONSUMMARIES

PracticeQuestionsforthissectionareinWorksheet6


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3. ROLES & RELATIONSHIPS BETWEEN ORGANISMS

Ecology is very much about relationships. This

section looks at some of the ways that different

species within an ecosystem relate to each other.

Predator - PreyThis describes situations where one animal eats

another.

examples... Predator Prey

Dingo eats Wallaby

Lion eats Zebra

Spider eats Insect

Dolphin eats Fish

Both predator and prey have major impacts on

each others distribution and abundance, and each

can cause the others population to rise and fall ina fairly regular pattern.

Notice that

Predator abundance is always lower than prey.

(Reasons for this are explained later)

The peaks and troughs of the predators

population always occur after those of the prey.

What happens:

1. The numbers of the prey species increasebecause of its breeding cycle, or seasonal increase

in available food.

2. This provides more food for predators, who

survive in greater numbers and reproduce more

sucessfully.

3. As predator numbers increase, more prey get

eaten and so the prey population decreases.

4. As prey numbers decline, less predators can

survive, so their numbers decline.

EACH ORGANISMS ABUNDANCE AFFECTS THE

OTHERS ABUNDANCE.

CommensalismCommensalism is a relationship in which one

organism benefits while the other is neither harmed

nor helped.

A good example is the remora, or sucker fish

which attaches itself to a shark with a suction cup

structure and hitches a ride. It does the shark no

harm at all. When the shark feeds, the remora feeds

on the debris and scraps from the sharks meal.

A simple example of commensalism is a birdnesting in a tree. The bird family gain the importantbenefit of a relatively safe and secure nest site, while

the tree neither gains nor loses.

Another example, seen commonly in rural areas isthe cattle egret (bird) which follows the cattlethrough the pastures, feeding on the insects whichare disturbed by the cows. The cow neither gainsnor loses from the relationship.

In Africa similar birds follow large grazing wildanimals for the same reason. However, the grazersgain the benefit of an early warning system whenthe birds react to approaching predators. Since bothspecies gain some advantage from the association,this is an example of mutualism (next page).

TIME (years)

PopulationSize

(ABUNDANCE)

PREY SPECIES

PREDATOR SPECIES

Populationpeaks

Shark with remora hitching a ride


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MutualismIn a mutualistic relationship, both species benefit.

Mutualism is much more widespread in nature than is

generally realized.

The classic example are insects (e.g. bee) and many

flowering plants. The insects total food supply isnectar and pollen from the flowers. As it gathers its

food the plants gain the essential service of pollination

of their flowers. Both benefit so profoundly that neither

can survive without the other.

Many grazing animals (e.g. kangaroos) eat a diet rich

in plant cellulose which is nutritious but difficult to

digest. These animals have a population of mutualistic

microbes living in their gut. The microbes are able to

break the cellulose down and make its nutrition

available to the animal, while the microbes gain a

secure, stable place to live and a permanent food

supply... both benefit.

A mother koala will regurgitate pap from her gut to

feed her baby. The pap contains the mutualistic

bacteria that the baby must have to digest the tough

gum leaves.

Another example is coral. The coral animal is a

polyp... a soft, hollow animal related to jellyf ish.

Inside the polyps flesh li ves another organism,

an alga (microscopic plant).

The polyp provides a secure home for the alga,which pays its way by sharing the food it makes

by photosynthesis. Both organisms gain

tremendous benefits from the relationship.

Parasite - HostParasitism is a relationship in which one organism feeds on another

without killing it, or even necessarily harming it significantly.

Some parasites, such as tapeworms, live inside their host and

absorb digested food without doing much harm. This way thehost stays healthy and the parasite has a secure

home and guaranteed food supply.

Other parasites, such as leeches and ticks, are casual

parasites who attach to a host, take a feed of blood, and then

drop off and live independently until hungry again.

More serious are the many micro-organisms which can cause

infectious diseases. These parasites include bacteria, viruses

and a few protozoans and fungi. They invade the hosts body,

feeding and reproducing so that the host

becomes sick and may even die.

Allelopathyis a relationship found particularly amongplants and fungi, in which one organism

directly inhibits the growth and development

of others by releasing toxins. The famous

antibiotic penicillin was discovered in the

fungus Penicillium because of its inhibiting

effect on the growth of bacteria.

Some trees and shrubs (including the pest

weed lantana) release inhibiting chemicals

from their roots. These inhibitors slow

down or prevent the germination and growth

of the seeds and seedlings of other plants.


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Competitionoccurs whenever two different species need to use

exactly the same resource, in the same way. The

resource in question may be a food, or nesting sites

or simply living space, such as when plants like

lantana or bitou bush grow over other plants.

Competition usually results in a winner and a loser.

One species will be slightly more successful than

the other, and its population will grow, while the less

sucessful competitor will decline in numbers and

may eventually become extinct in the ecosystem.

Sometimes what seems like competition turns out

not to be. For example, the lion and the leopard are

both large African predators, often living in the same

areas and both feeding on the herds of grazing

animals.

However, careful studyreveals that their hunting

techniques are so different

that they tend to prey on

different species and

different categories

(e.g. young rather than

adults) so they are in

fact NOT competing and

can both survive in the

same habitat.

This situation is called resource partitioning.

It is known from

fossils that the

Thylacine

(Tasmanian tiger )

was once widespread

as one of the mainpredators on

mainland Australia.

However, its numbers

rapidly declined after

the introduction of

the dingo from Asia

about 10,000 years

ago.

It seems the dingo was a more sucessful predator

and out-competed the Thylacine on the mainland.

The dingo was never introduced to Tasmania, so

there the tigers survived until driven into totalextinction by the impacts of European settlement.

TIME (years)

ATYPICALCOMPETITIONGRAPH

PopulationSize(ABUN

DANCE)

Thylacine

Original populationreasonably stable

Dingo

ThylacineExtinct

Dingointroduced

Worksheet 5 RelationshipsFill in the blank spaces.

An animal which k il ls and eats another animal is

called a a)......................................... The animal it

eats is its b)............................ Each ones

population abundance affects the other. For

example, if the predator population increases,

the prey population will c).............................

because d)............................................................On a graph, the peaks & troughs will match

each other, but the predators graph will always

be e)............................ and f)...................................

than the preys graph.

A parasit e is an organism which

g)............................ on its host without

h).................................... A good example is the

i)............................................. which lives in the

gut of its host, eating the digested food. Other

parasites such as j)...................................... and

.................................... feed on the hosts blood.

A relationship in which one organism gains an

advantage, while the other neither gains nor

loses, is called k)............................................ An

example is the shark and the l)..............................

Mutualism is when 2 organisms

m).............................................................................

A good exampl e is n).... .... .... .... .... and

.....................

Many grazing animals get help to digest thetough fibres of plant food from mutualistic

relationship with o)....................................... living

in their gut.

Some plants and fungi produce chemical toxins

which p)............................................ the growth of

other organisms. This relationship is called

q)......................................................

Competition is when 2 organisms both need

to use r)................................................. in an

environment. Usually, the result of competition

is s)..........................................................................

Dingo


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Worksheet 6 Practice Questions Sections 2

Worksheet 7 Practice Questions Sections 3

Multiple Choice1. Which of the following is a biotic factor in an

ecosystem?

A. Light intensity.

B. Soil type

C. DiseasesD. Temperature range.

2. The streamlined shape of a dolphin is an adaptation

to:

A. the high buoyancy of water.

B. low availablity of gases in the sea.

C. large temperature variations.

D. the high viscosity of water.

3. Many seaweeds have brown or red pigments

because:

A. these absorb the predominately blue light thatpenetrates underwater.

B. it camouflages them among the rocks of the sea

floor.

C. red and brown light penetrates water more than

other colours.

D. this helps them control their temperature by

absorbing more heat.

Multiple Choice

1. The following graph shows the changes inpopulation numbers for a prey species and 4 other

species. Which one (A, B, C or D) is most likely to be

the predator?

2. The cleaner wrasse is a small fish of the coral reef

which feeds on the parasites clinging to other fish.

Many larger fish will queue up to wait for a cleaner

wrasse to pick off their parasites.

The relationship between the cleaner wrasse and the

larger fish is an example of:

A. Mutualism

B. Commensalism

C. Allelopathy

D. Competition

Longer Response Question

4. (4 marks)Construct a simple table and fill it in to compare theterrestrial and aquatic environments with respect

toviscositybuoyancytemperature variation

and availability of light

Preyspecies

AB

CDTime

ABUNDANCE

Longer Response Questions

3. (5 marks)a) Define the term mutualism .

b) Give an example of mutualism, naming 2organisms and outlining how each is affected bythe relationship.

4. (5 marks) In nature, allelopathy is a method of beating yourcompetition.Discuss this statement briefly, giving definitionsand examples as appropriate.


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4. THE FLOW OF ENERGY & MATTER IN AN ECOSYSTEM

Cycling of MatterWithin any ecosystem the important chemicals of

life tend to be re-cycled.

The water cycle of nature is well known, and you

should be familiar with the Oxygen-Carbon cycle.

Other chemicals that are recycled within

ecosystems include Nitrogen, Calcium and

Phosphorus... in fact ALL the chemicals get used

over and over again.

Energy Inputs & OutputsUnlike the chemicals, energy cannot be recycled.

As it is used i t must be replaced from outside the

ecosystem.

The ultimate source of ALL the energy in an

ecosystem is the SUN. The Sun provides the heat

to keep each ecosystem at a livable temperature,

but it is the LIGHT of the Sun which powers all life.

How Organisms Use EnergyEverything that an organism does requires energy.

Organisms:-Move

Grow and Repair body tissueReproduce

Seek, Eat and Assimilate their food

Respond to happenings around themKeep their bodies warm

Cellular Respirationis the process which releases the energy stored in

food. It takes place in every living cell on the planet and

after photosynthesis (next topic) is the next most

important biological process on Earth.

Although the process can be written as a simple

chemical reaction, this is very deceptive. Cellular

respiration actually takes place as a sequence of

about 50 chemical steps... the equation above is

merely a summary of the overall process.

Dont forget that the essential product of

respiration is the energy-carrier ATP. The CO2and H2O are merely waste products to be

recycled in the ecosystem like all chemicals.

A common misconception is that plants doPHOTOSYNTHESIS and make food, whileanimals do RESPIRATION to use the food.

Its true that plants do photosynthesis and makeall the food on Earth, but respiration is carriedout by all living things... animals AND plants.

Luckily for us animals, the plants carry outenough photosynthesis to feed themselves,

AND produce a surplus to feed us as well.

SUN

Light PLANTScapturelightenergyduringPhotosynthesis

EnergyisstoredintheFOODproducedbyplants

Allorganismsusetheenergyinfoodtopowertheirlife

functions.TheprocessofRespirationreleasestheenergyinfood.

INPUT

OUTPUTwasteheatenergy

Glucose + Oxygen Carbon + Water(sugar) Dioxide

WasteproductsMajorenergycompoundinfoods

in air

ATP

Energy-carryingchemical used inall cells to power

life processes.

Theprocess

transfersene

rgyto

C6H12O6 + 6O2 6CO2 + 6H2O

energy transfer ATP

Respiration

ANIMALS

PLANTS

CO2

O2

Photosynthesis


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Food ChainsPlants are food PRODUCERS.

They capture light energy by the process of photosynthesis, and store it as the chemical energy in food.

Al l other organisms are CONSUMERS of food. They rely on eating the plants or other animals.

So, in any ecosystem there is a chain of feeding, based on the plants... a food chain .

GRASS KANGAROO DINGO

Plant Herbivore Carnivore

Producer 1st order 2nd order Consumer Consumer

1st Trophic 2nd Trophic 3rd Trophiclevel level level

(trophic refers to feeding)

NOTES:

1. The arrows in a food chain show the direction that the energy flows. The arrows must never be reversed.

2. Note the different ways to describe each organisms role in the chain. Try not to confuse the different methods...

e.g. a 1st Order Consumer is at the 2nd Trophic Level... etc.

The Role of the Decomposers

All along the food chain organic wastes are produced.

Dead leaves from plants, body wastes and shed skin and fur

from the animals are just a few examples.

This left-over waste material is food for a very important

group of organisms... the decomposers. The maindecomposer organisms are the microscopic bacteria and

the soil fungi. These organisms feed on the scraps and

wastes and in doing so, cause wastes to decay and be

broken down into very simple chemicals such as CO2 and

nitrate and phosphate ions.

THIS IS ESSENTIAL TO THE RECYCLING OFTHE CHEMICALS IN AN ECOSYSTEM.

So the decomposers get rid of all the wastes and clean up

the environment, and they ensure that the vital chemicals

are recycled into air or soil for re-use by the plants... and so the food chains cont inue.

Mushroomsandtoadstoolsarethereproductivestructuresofsoil-livingfungi

Thearrowshowsthedirectionthatfoodenergyflows.NEVER DRAW THEM BACKWARDS!Everyfoodchainmustbeginwithaplant

is eaten by is eaten by


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Food WebsAlthough we can best understand the flow of energy by a food chain,

in fact simple food chains never exist by themselves in nature.

Kangaroos don t just eat grass, and dingoes don t jus t eat wallabies.

The real feeding relationships in an ecosystem can only be described by a food webwhich is made up of many inter-connected food chains.

A food web diagram allows us to analyse the f low

of energy (stored in food) through the ecosystem

and to make certain predictions...

Example Questions and AnswersQuestion:

List all organisms which are 1st order consumers.

Answer:

Limpets, periwinkles, chitons, mussels &

zooplankton.

Question:

Which organism is at the highest Trophic Level

above?

Answer:

The large fish, which is at the 5th trophic level.

Question:

What might be the effect on the mussel population

if there was an increase in the octopus population?

Answer:

If there were more octopus they will eat more

mussels, so the mussel population woulddecrease.

Example: FOOD WEB IN A ROCK POOL large fish

starfish octopus small fish

mussels

limpets periwinkles chitons zooplankton(microscopic animals)

green algae phytoplankton(microscopic plants)

Hints on Constructing a Food WebTo keep it simple and read-able (K.I.S.S.) when constructing a food web:

always s tart with the producers (plants) at the bottom and work upwards

try to keep the members of the same trophic level in-line in the diagram.

(not always possible, because some organisms may be feeding at more than onetrophic level... look at the mussels in the diagram above.)

Question:

If a disease wiped out all the mussels in a

particular area, what effect might this have on

the chiton population?

Answer:

(Chitons are not directly connected to mussels,

so you might think thered be no effect, but...)

If there are no mussels to eat, the octopus might

eat more chitons. Therefore the chiton

population could decrease.

OR

Without mussels to eat, the octopus might eat

more starfish. This could mean less chitons

being eaten by starfish so the chiton population

could increase.

This demonstrates the difficulty ofmaking predictions about natural foodwebs... the consequences of change

can be quite unpredictable!


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Biomass

You are what you eat goes the old saying, and it is

literally true that every molecule of your body is bui lt

from the chemicals that you have eaten as food over

your lifetime. Your body weight is your Biomass...

the mass (weight) of living flesh in you.

An average person eats at least 250 kg of food per

year and drinks at least 500 litres of liquids. So why

arent we all as big as an elephant? Simply because

we all produce roughly the same mass of wastes

and excrete them so that our biomass stays more or

less the same. (Unless still growing, of course).

In ecology, we deal with the total biomass of an

entire population, or of the whole community. For

example, if there are 200 starfish living in a particular

rockpool, and each has a mass (on average) of 50

grams, then the biomass of starfish in the rockpoolis 200 x 50 = 10,000 g = 10 kg.

It is always found that the biomass of plants is more

than the biomass of herbivores, which is more than

the biomass of carnivores, and so on. Why?

Everything you do requires energy, which you get

from cellular respiration...

C6H12O6 + 6O2 6CO2 + 6H2O + ATP

...and as you breathe out you excrete the waste

CO2 (plus some water vapour) and so you lose a

little of the mass of the food you previously ate.

...and as you use the energy of the ATP molecules,

the energy is converted to low-grade heat and

dissipates into your surroundings. This energy is

lost, and cannot be re-used by living things.

In any ecosystem it turns out that about 90% of the

food/energy taken in at any trophic level, is lost as

wastes and low-grade heat. (Thank goodness for

the Decomposers to get rid of all that waste!)

This means that in a food chain, only about 10% ofthe biomass and energy at any trophic level is

available to be eaten by the next trophic level

organisms.

The result is a BIOMASS PYRAMID.

2ndTrophicLevel

3rdTrophicLevel

4thTrophicLevel

1stTrophicLevel

PYRAMID OFBIOMASS

&

ENERGY

So, for the food chain

GRASS KANGAROO DINGOif there was (say) 100,000 kg of grass in an area, then

this could not support more than about 10,000 kg of

kangaroos, and only about 1,000kg of dingo biomass.

The approximate population numbers would be:

5 million grass plants feeding about 400 kangaroos,

feeding just 50 dingoes... a pyramid of numbers too.

This is why very few food chains in nature have more than 5 or 6 trophic levels...the available food & energy becomes too small to support higher level predators.

Pyra

midsha

pe

BiomassofProducers(Plants)

10%available

BiomassofHerbivores

10%

10%90%ofBiomassandEnergy lost

90%ofBiomassandEnergylost

90%ofBiomassandEnergylost


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Worksheet 8 Practice Questions Section 4 (2 pages)

Multiple Choice

1.

Which of the following statements about ecosystems

is generally true?

A. Energy is re-cycled, while chemicals have to be

constantly supplied.

B. Both matter and energy are re-cycled.

C. Matter is re-cycled, while energy has to be


D. Both matter and energy have to be


2.

The essential product of cellular respiration is:

A. Glucose

B. Oxygen

C. Carbon Dioxide

D. ATP

3.

In the following food chain:

algae > limpet > octopus > fish > shark

the herbivore and the organism at the 4th Trophic

level are respectively:

A. limpet and shark

B. limpet and fish

C. algae and fish

D. algae and shark

4.Soil bacteria usually have the role in ecosystems of:

A. Decomposers

B. Disease causing parasites

C. Producer organisms

D. Epiphytes

5.

In a certain area, the biomass of species is:

Species Biomass (kg)

P 10,000

Q 5,000,000

R 100,000

S 500

If these 4 organisms are involved in the same food

chain, then the order in the food chain is most likely:

A. S > R > P > Q

B. P > Q > R > S

C. Q > S > P > R

D. Q > R > P > S

Longer Response QuestionsMark values given are suggestions only, and are to

give you an idea of how detailed an answer is

appropriate. Answer in the spaces provided.

6. (8 marks)

a) Write a word equation to summarize the process

of cellular respiration.

b) The process makes energy available to living

cells.

i) What is the original source of this energy?

ii) How does the energy get into an ecosystem?

iii) In what form is the energy passed from

organism to organism?

7. (4 marks)

In a seaside rockpool, the total biomass of all

visible plants, herbivores and carnivores was

estimated as follows: Plants 10 kgHebivores 20 kg

Carnivores 2 kg

a) On these figures alone, could the rockpool be a

viable, stable ecosystem? Explain your answer.

b) Over time, the rockpool community is studied

and it is found to be very stable and more-or-less

unchanging. Suggest how this might be possible.

Worksheet9isaSummaryWorksheetforthissection


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Worksheet 8 Continued

9. (8 marks)From your diagram for Q24 answer the following.a) Name three 2nd-order consumers.

b) Name an organism which occupies more than one trophic level.

c) Write the longest food chain within this web.

d) Name 2 organisms who could well be competitors.

e) There is a world-wide trend of decline in amphibian populations. If the frog populationin this food web was drastically reduced, what might happen to the:

i) insect population?

ii) mouse population?

f) Comment on a human impact apparent from the food web for this ecosystem.

8. (5 marks)The following observations were made about the feeding relationships in an Australianrural ecosystem. Use the information to construct a food web diagram.

Honey-eater birds feed on the nectar and pollen of native shrubs. These shrubs are also eaten by insects

and wallabies. Grass is eaten by insects, rabbits and wallabies, while mice feed on the grass seeds. Frogseat insects, while dingoes prey on rabbits and wallabies. Kookaburras hunt snakes and frogs. The snakesfeed on frogs, mice and take the eggs and babies from honey-eater nests.


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Adaptations are special characteristics thathelp an organism survive in its environment.

For example,the black bear

of North

America has a

thick coat of fur.

This is a

structural

adaptation to its

environment.

The fur helps

insulate the

body to keep it

warm in the cold climate in which it lives.

Other structural adaptations that have already been

mentioned in previous sections include:

streamlining of many aquatic animals to deal with

the high viscosity of water.

large, broad, leaves of plants living on the

rainforest floor, to cope with the low light levels.

the bony skeleton of most terrestrial animals

needed to support the animal against gravity.

Another category of adaptation is physiological

adaptation. (Physiological refers to the way the body

works or functions)

Previously mentioned examples include:

animals shivering when cold, and sweating when

too hot.

freshwater fish excreting water constantly to

remove excess water from their bodies. This is

controlled by the functioning of their kidneys.

One of the classic physiological adaptations is the

kidney function of many desert animals. In an

environment where water is scarce, these animals

conserve body water by producing only small

amounts of very concentrated urine.

In some cases, such as desert mice, their kidneys are

so efficient at retaining water that they do not need to

drink, but can survive on the metabolic water

produced by cellular respiration.

A third category is behavioural adaptation, which is

where an animals instinctive behaviour helps it

survive and thrive in its environment

Dangers of Inferring AdaptationsYou need to be careful when examining any organism

for its adaptations because it may require careful study

to be sure of the real reason for some characteristics.

For example, it is possible that the adaptation you

observe could be inherited from ancestors who lived

in a different environment, and it is not a help to

survival in the current habitat.

Also, its not always easy to decide what survival

advantage a particular characteristic may give.

For example:

is the magpies colour scheme an adaptation which

helps it survive because it gives:

camouflage?

or temperature control?

or sexual attraction for mating?

or identification, to keep a group together?

Only careful study will reveal the truth

5. ADAPTATIONS OF ORGANISMS TO THEIR ENVIRONMENT

Thislizardissunbakingtowarmitselfupforactivehuntingforinsects.

Ifitbecomestoohotitwillmoveintotheshadetocoolitself.


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Worksheet 10 Adaptat ionsFill in the blank spaces.

Special characteristics which help anorganism survive in its environment arecalled a)........................................

Some of these are structural : theyinvolve special structures, such as thefur of a bear which b)...............................in a cold c limate.

Another example is how many aquaticanimals are c)...................................... toallow them to move more easily throughwater, which has a highd)............................

The second category of adaptations arethose that are e)......................................,

or related to the functioning of the body.

For example, an animal mightf)........................ when too hot, org)....................................... if too cold.

Many desert animals have highlyefficient kidneys so they produceh)......................... amounts of highlyi).................................... urine, in order toj)....................................... water.

The third category of adaptations isk).................................................. Forexample, reptiles cannot regulate theirbody temperature physiologically, sothey use behaviours instead. They willl).................................................. whentoo cool, and seek m)...............................

when too hot.

Worksheet 9Flow of Energy and MatterFill in the blank spaces.

In any ecosystem, the chemical resources

tend to be a).........................., but the energyis used up and must be constantlyb).......................................... The source of allthe energy is the c)................... The energyis captured by the d).......................... in theprocess ofe)...................................................Thisconverts light energy into the energystored in the f)............................. molecules.

Organisms need energy for all the lifeprocesses such as moving around,g).......................... and ...........................The energy of food is released by theprocess of h).................................... Thisrequires the gas i)............................ Theproducts are the chemical wastesj)........................... and ........................... andthe energy chemical known ask).....................

Energy is passed from one organism toanother as food, and the flow of energythrough an ecosystem is al)................................. In any food chain, the

plants are the m)................................, andanimals are n)......................................

The Decomposers are vital to get rid ofwastes and dead scraps and too)....................................... vital chemicals.Single food chains rarely exist in nature.Instead, a number of food chains whichp)........................... with each other, form aq)..................................... .........................

The total body weight of all the individualsof a species in an ecosystem is known asthe r)................................ There is alwaysabout 10 times more r)............................... ofplants than of s)....................................because about 90% is always lost aswastes. Because the biomass decreasesrapidly up through any food chain it isreferred to a biomass t)............................


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Human culture is the learned behaviours we have

accumulated over the millenia. Our culture includes

language, art, music, customs and TECHNOLOGY.

It is our over-population, and our complex, industrial

technology that impacts on natural ecosytems...

Loss of HabitatVery simply, humans clear forests, fill wetlands and

divert streams to make room for our towns and cities

and for our agriculture. For example, only about 3%

of Australian rainforests remain, from those present

200 hundred years ago.

Clearing of natural environments is disaster for

many species. They are specially adapted to their

habitat and cannot survive elsewhere.

PollutionMany human activities produce chemicals which

can harm the environment if released.

Acid rain results from gases such as sulfur dioxide

(SO2) released from burning of fossil fuels,

especially coal. The gas dissolves in rainwater

forming an acid solution that can seriously affect

forests, lakes and wetlands by killing some

organisms so that food chains are disrupted.

Pesticides and industrial poisons, even in very small

amounts can build up in living communities by

biological magnification ...

example: the level of toxic chemical in a shrimp

might be quite low, but a fish which eats many

shrimp in a year ends up with a concentration of

toxins 100 times higher... and so on up through the

food chain.

Scientists are currently alarmed by a world-wide

decline in populations of amphibians (frogs &

toads). It is suspected that various human-made

chemicals are disrupting the reproduction and

development of many species which are vital links in

the food webs in many ecosystems.

Eutrophicationoccurs when rivers and streams are over-fertilized

by human sewerage and agricultural run-off.

Although our sewerage may be thoroughly treated

to make it safe to the environment, the effluent still

contains many minerals which act as a fertilizer.

Typically, the treated effluent from our sewer

systems is discharged into waterways. Similarly,

when farmers use fertilizer on their crops and

fields, some will eventually be washed into creeks

and rivers during rainy weather.

The result is that algae living in the waterways are

stimulated to grow in over-abundance, often

choking waterways and blocking light from other

water plants. Later, great masses of algae die offand their decay uses up all the oxygen in the water,

so that many fish and other organisms suffocate.

Introduction of Alien SpeciesThe European settlers to Australia brought many

species from other places and released them into

the new environment. The list includes plants such

as prickly pear, lantana and bitou bush, and

animals such as rabbits, foxes, pigs, camels, and

cane toads.

All of these species, and many others, have

become major problems in the ecosystems,

because:

the aliens find themselves in an environment in

which the normal predators and diseases are not

present to keep their population in check

they are often more ruthlessly efficient in using

resources, and so they out-compete the

native species.

Many ecosystems around the world

are being disrupted by alien species

introduced by humans.

6. HUMAN IMPACTS ON ECOSYSTEMS

Toxinconcentration=1unit

Toxinconcentration=10units

Toxinconcentration=1000units

BiologicalMagnification

PricklyPearCactus


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Worksheet 11 Practice Questions Sections 5 & 6

Multiple Choice

1.One of the adaptations visible in the

North American beaver is a large, broad,flat tail.

This adaptation probably helps thebeaver survive because it:

A. gives it more balance on land.B. helps it to carry twigs & branches.C. protects against predator attack.D. helps it to swim and steer in water.

2. Eutrophication is when:

A. pollut ing chemicals in theenvironment become moreconcentrated up a food chain.

B. aquatic habitats suffer from algalblooms due to over-fertilization.

C. gases from burning of foss il fuelscause waterways to become acidic.

D. an introduced species over-populates an ecosystem.

3.

Many animals seek shade when itbecomes too hot in the Sun. This is anexample of an adaptation which isprobably:

A. st ructural.B. physiological.C. behavioural.D. learned.

Longer Response QuestionsAnswer in the spaces provided.

4. (4 marks)

a) Explain what is meant by anadaptation.

b) Give an example of an adaptation foreach of the following situations.i) A structural adaptation (ianimal) to acold climate.

ii) A plant adaptation to low light levels onthe rain forest floor.

iii) An adaptation for water conservation ina desert animal.

5. (3 marks)Outline a human impact on a named typeof ecosystem.


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CONCEPT DIAGRAM ( Mind Map ) OF TOPICSome students find that memorising the OUTLINE of a topic

helps them learn and remember the concepts and important facts.

Practise on this blank version.

A LOCAL

ECOSYSTEM


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Answer Section

Worksheet 1

a) where b) interactingc) food d) hiding / escapinge) transect f) straight line

g) which species are presenth) Abundance i) quadratsj) average number k) study areal) doing more quadrat dropsm) Capture - Recapturen) marking/tagging o) releasingp) capture q) marked/taggedr) total populations) mixing randomly back into the population

Worksheet 2

Quadrat Study Problems

1.Average per quadrat = 46 / 10 = 4.6Study area = 20 x 30 = 600 m2

Estimated = Average count x Study areaPopulation per quadrat Quadrat area

= 4.6 x 600 / 0.25= 11,040

Population estimate = 11,000 starfish approx.

2.Average per quadrat = 105 / 20 = 5.25Paddock area = 300 x 400 = 120,000 m2

Estimated = Average count x Study area

Population per quadrat Quadrat area= 5.25 x 120,000 / 0.5= 1,260,000 weeds approx.

Capture - Recapture Problems3.

Estimated = 1st capture x 2nd capturePopulation no.marked in 2nd capture

= 230 x 15618

= 1,993Estimated population 2,000 lizards

4.Estimated = 1st capture x 2nd capture

Population no.marked in 2nd capture= 65 x 48

12= 260 possums

If the possums enjoy being trapped then therecapture sample contains a disproportionately HIGHnumber of tagged animals, who have come back tothe traps deliberately. Mathematically, if the number 12 is too h igh, then the answer (260) is too low, sothe real population is h igher than the estimate.

Worksheet 31. B 2. B 3. D 4. A

5. Species K is not widely distributed, but seems

confined to the hilltop (higher elevation).

Species L seems to occur only near water, on the

banks of ponds and creeks.

6. Estimated = 1st capture x 2nd capturePopulation no.marked in 2nd capture

= 537 x 83245

= 9,929

To nearest 1000, Estimate = 10,000 trout .

7.

a) i) Area = length x width = 120 x 85 = 10,200 m2.

ii) Average = (8+14+2+5+9+22+3+0+12+7) / 10

= 82 / 10

= 8.2 plants / quadrat

b) Estimated = Average count x Study areaPopulation per quadrat Quadrat area

= 8.2 x 10,200/0.25= 334,560

Estimate = 335,000 plants approximately

(Note: it is NOT appropriate to give an answer of334,560 since this suggests that the process wi llcalculate the exact number of plants. It is astatistical estimate only, and answers should berounded off)

c) Make more drops of the quadrat.

Worksheet 4Biotic Factors Abiotic Factorsprey lightdiseases oxygenpredators water food plants soilcompetitors temperature

exposureacidity

Fill in the blanksa) terrestrial b) aquaticc) Viscosity d) low viscosity

e) higher viscosity f) streamlinedg) flotation h) morei) support j) much lessk) fur/fat/feathers l) sweatm) oxygen n) dissolveo) gills p) conserveq) waterproof r) excretions) osmosis t) loseu) excrete v) rainforestsw) staghorns/orchids etc

x) large/broad/packed with chlorophyl l

y) colours / wavelengths z) Red/orange

aa) blue ab) pigments

ac) plants ad) dead material

ae) chemosynthesis


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Worksheet 5

a) predator b) prey

c) decrease d) more prey will be eaten

e) lower f) later / after

g) feeds h) killing it

i) tapeworm j) ticks, mosquitoes, leeches

k) commensalism l) remora ( sucker fish )

m) both gain a benefit n) bee & flowering plants

o) bacteria / protozoa p) inhibit / s low

q) allelopathy r) the same resource(s)

s) one survives and thri ves, the other declines.

(one wins, one loses)

Worksheet 61. C 2. D 3. A

4. Terrestrial Aquatic

Environment Environment

Viscosity low high

Buoyancy low high

Temp.variation high low

Light avail. good gets less withdepth

Worksheet 7

1. C 2. A

3.

a) Mutualism is a relationship between 2

different species in which bo th gain a benefit.

b) Honey bee and flowering plant.

Bee gains food supp ly.

Plant achieves pollination of its flowers.

4.

Allelopathy is when one species produces a

chemical or toxin to inhibit the growth and

development of other species.Allelopathy is a method of dealing with competitors,

such as the lantana plant producing toxins in its roots,

which inhibits other plant species. This allows lantana

to out-compete other plants and gain more soil

minerals and light.

(Note: this is why lantana is such a noxious

weed... its a great competitor when introduced

to a new environment without its natural

diseases and enemies.)

Worksheet 81. C 2. D 3. B 4. A 5. D6.a) Glucose + Oxygen Carbon + Water + ATP

Dioxideb) i) The Sun

ii) Energy is captured by plants in photosynthesis.

iii) As food (containing chemical potential energy)7.a) No. Stable ecosystems always have about 10times more biomass of plants than herbivores.The rockpool has less plant biomass thanherbivores. This is not sustainable.

b) The biomass figures include only visibleplants. There may be a large biomass ofmicroscopic algae and plankton not accountedfor in the figures.or,Perhaps the herbivores in the rockpool are notjust feeding on the plants present , but leave the

pool at high tide to feed elsewhere.or,The community might be sustained by extrabiomass which washes into the pool with wavesand tides and feeds the herbivores.8.

kookaburras

snakes

frogs dingoes

honey

eaters insects mice wallabies rabbits

native shrubs grass

9.a) snakes, frogs, dingoesb) snake or kookaburrac)nat.shrubs>insects>frogs >snakes >kookaburrasd) wallabies and rabbits (best answer)(Note: other poss ible answers are not as good.e.g. snakes & kookaburras both eat frogs, butkooks also eat the snake, so they are not justcompeting for frogs.

Honey-eaters and insects both eat shrubs, butdifferent parts of the plant, so not competing.Same with mice v rabbits... not eating the sameparts of plants.)

e) i) without predators, the insect populationshould increase.

ii) If less frogs, then snakes might eat moremice. Therefore mouse population maydecrease.

f) The rabbit is an alien species introduced toAustral ia from Europe. In the absence of itsnatural enemies and diseases, it has over-populated at the expense of native species.


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Worksheet 9

a) re-cycled b) replaced / input

c) Sun d) plants

e) photosynthesis f) food (glucose)

g) growing, reproducing, responding etc

h) cel lular respirat ion i) oxygen

j) water & carbon diox ide k) ATPl) food chain m) producers

n) consumers o) re-cycle

p) inter-connect q) food web

r) biomass s) herbivores

t) pyramid

Worksheet 10

a) adaptations b) insulates it

c) streamlined d) viscosity

e) physiological f) sweat

g) shiver h) smalli) concentrated j) conserve

k) behavioural l) sunbake

m) shade / shelter

Worksheet 11

1. D 2. B 3. C

4.

a) An adaptation is a special feature of an

organism, which helps it to survive in itsenvironment.

b) i) A thick fur coat, or feathers, or layers of

blubber (fat) all act as heat insulators.

ii) Large, broad leaves capture what light is

present.

iii) Kidneys that produce small amounts of

concentrated urine, so less water is lost by

excretion.

5. (many different answers possible)

Humans clear forests, fill and drain wetlands etcfor agriculture and to build towns, roads etc.

This results in loss of habitat for many forest

species which are adapted to particular

environments and cannot live elsewhere.

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