Diversity in living organisms
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Transcript of Diversity in living organisms
CLASSIFICATION : Science of arranging organisms in series of groups and
subgroups on the basis of their similarities and dissimilarities.
Aristotle classified organisms on the basis of their habitat means the place where they live , in water , in air and on land.
Basic characteristics of classification
Nature of cells : prokaryotic or eukaryotic
Cellularity : unicellular or multicellular
Level of organisation : cellular ,tissue ,organ and
organ systemMode of nutrition :
autotrophic and heterotrophic
Classification and evolutionTime is the key factor which helps in development of complex organisms
from the simple ones.Charles Darwin firstly gave the idea of evolution in 1859 in his famous
book ‘the origin of species’.Those organisms which have ancient body design and not
changed much are called primitive organisms.
Those who acquired certain special characters during the time period are known as advanced or higher
organisms
BiodiversityBiodiversity is the term
used for the various forms of life found in a
given area.These life forms depend
on each other and on the environment and
results in a stable community.
Human also is the part of this biodiversity.It is estimated that
there is about 10,000,000 species on this planet , we know only about 20,00,000
species.
Hierarchy of classificationErnst Haeckel , Robert Whittaker , carl woese have tried to classify all living
organisms into broad categories. R.Whittaker proposed five kingdom system
which is widely used .This kingdom includes monera , protista ,
fungi , plantae and animalia.Carl woese divided monera into archaebacteria and eubacteria.
Further classificationFurther classification is
done by naming the sub groups at various levels
as given :Kingdom-phyllum\
division-class-order-family-genus-species
Kingdom moneraKingdom protista
Kingdom fungiKingdom plantaeKingdom animalia
Kingdom : moneraUnicellular organismsNucleus and cell organelles are absent May or may not have cell wallAutotrophic or heterotrophicAble of nitrogen fixation Reproduce by asexual methodsBacteria , cyanobacteria and mycoplasma.
Kingdom : Protista
Unicellular organisms.A well defined nucleus and cell organelles arepresent . They may be autotrophic or Heterotrophic. Some of these organisms have appendages like cilia and flagella for movement.They reproduce by both sexual and asexual methods.Diatoms , protozoan's arefew examples.
Kingdom : fungiHeterotrophic eukaryotic
organismsSaprophytes
Cell wall made of chitinSome of them live in close
relationship with certain algae and plants forming lichens and mycorrhizaeSome of them have the
ability of being multicellularYeast ,mushroom and
rhizopus.
Kingdom : plantae They are
multicellular eukaryotic organisms.
This kingdom includes all the plant species.
They are autotrophic and
prepare their own food.
They are further classified into five major divisions.
Division : ThallophytaBody of the organisms is not differentiated into organs .Mainly aquatic found in marine and fresh water.Tissue for conduction of material and for mechanical strength is absent.They are covered by mucilage.Reproduce by vegetative , asexual and sexual reproduction.Algae is example of this division.
Division : BryophytaPlant body is differentiated
into leaf , root and stem like structures.
Special conducting tissues are not present.
These are known as amphibians of plant
kingdom.Reproduce by vegetative ,
asexual and sexual reproduction.
Funaria , anthoceros and marchantia are few
examples.
Division : PteridophytaPlant body is differentiated into leaf , stem and roots.
They also have conductive tissues.
All the above discussed plant types doesn't bear seeds instead they bear
spores. They are also known as cryptogams.
They require water for the purpose of reproduction.
Fern , adiantum and selaginella are few
examples.
Division : GymnospermsThese plants bear naked seeds means seeds which are not enclosed in fruits.These are perennial , evergreen trees having woody trunk.They bear cones in which seeds are placed.Sequoia sempervirens is the largest tree found on earth [125 meters] is an example. Other examples are pinus and cycas.
Division : AngiospermsBear seeds covered by special organs known as fruits.They bear flowers as their reproductive organs.Embryo in seed has special structure called cotyledons which act as seed leaves at the time of germination.They are divided into two groups : monocots and dicots.Wheat , rice , rose and tomato are examples of this division.
Kingdom : AnimaliaMain characteristics of this kingdom are as follows :These are eukaryotic organisms of heterotrophic nature.These are multicellular organisms.Their cells do not bear cell walls and chloroplasts.They are further subdivided into following categories:
Phylum : PoriferaThese animals bear small holes on their
body surface.They are aquatic and sedentary means non
motile.They have cellular level
of body design.They bear hard external
skeleton and have a canal system for the
distribution of food and gases.
Spongilla and sycon are the examples.
Phylum : CoelentrataThey are aquatic
animals and have tissue level of body
design.They have a body
cavity called coelom so named coelentrata.
They may be solitary or colonial.
They have special stinging cells called cnidoblasts so also known as cnideria.Hydra , obelia and
physalia are few examples.
Phylum : Platyhelminthes Show bilateral symmetry and are triploblastic means have three germ layers.They are dorsoventrally flattened so also called flatworms.They are either free living or parasitic.They have tissue level of body design.They do not have any body cavity.Planarian and liver flukes are examples.
Phylum : NematodaThese animals show
bilateral symmetry and are triploblastic means have
three germ layers.They are cylindrical in
shape.They have pseudocoelom.
They have tissue level of body design.
They are mainly parasitic in nutrition.
Ascaris and wuchuraria are examples.
Phylum : AnnelidaShow bilateral symmetry and are triploblastic.They are cylindrical in shape and have a true body cavity.Organ system level of body design is found.Body is divided into small segments called annuli so phylum is also known as annelida.They are found on both land and water.Earthworm and leech are examples.
Phylum : ArthropodaThese animals show
bilateral symmetry and are triploblastic means
have three germ layers.They have a true body
cavity which is blood filled.
Organ system level of body design is found.
Open circulatory system is found in these animals.Largest group of animals.
They have jointed legs.Cockroach , housefly ,
butterfly are examples.
Phylum : MolluscaBody cavity is highly
reduced.These animals show
bilateral symmetry and are triploblastic means
have three germ layers.They also have open
circulatory system.They have kidney like
structure for excretion.A highly muscular foot is
used for movement.Pila and chiton are
examples.
Phylum : EchinodermataThese are spiny skin organisms.They are free living animals found only in marine water.They are triploblastic and have true body cavity.They have a tube system for the purpose of movement.They show high power of regeneration.Starfish and sea urchin are examples.
Phylum : Protochordata
These animals show bilateral symmetry and are triploblastic
means they have three germ layers.They are cylindrical in shape and have a
true body cavity.They also have a notochord at any stage of life which provide surface for the attachment of
muscles and to provide support.
Amphioxus , balanoglossus are
examples.
Phylum : VertebrataThey have
notochord at any stage of life.
They have a dorsal nerve chord.
They are triploblastic.
They have paired gill pouches.
They have true body cavity.
It includes classes : pisces , amphibia , reptilia, aves and
mammalia.
Class : PiscesThey are aquatic
animals found in fresh and marine water.Skin is covered by
scales or plates and have gills for
respiration.Body is streamlined and
has a tail.They have two
chambered heart and are cold blooded.
Skeleton is made up of either cartilage or bone.
Scoliodon and labeo rohita are some
examples.
Class : AmphibiaThey are animals with uncovered skin which help in gas exchange.They have three chambered heart and are cold blooded.They are found in both water and on lad.They lay eggs without any hard shell.Frog and salamanders.
Class : ReptiliaThey are terrestrial as
well as aquatic.Skin is covered by
scales.They are cold blooded
animals mostly having three
chambered heart except crocodile.
Their eggs are covered by a hard
shell.They breathe through
lungs.Examples are snakes
and tortoise.
Class : AvesThey have four
chambered heart and are warm blooded.
They breathe through lungs.
They lay eggs covered by hard shells.
Their body is covered by feathers and are very
good fliers.They do not have teeth
and bear beak and claws.All the birds are
examples.
Class : MammaliaThey have four chambered heart and are
warm blooded.They breathe through lungs.
They have mammary glands for the production of milk.
They have hairs and nails as well as sweat and oil glands.
They give birth to young ones except platypus and echidna.
All the milk producing animals including humans.
All the milk producing
Need for Nomenclature :To solve the problem of many
names for any organism in different areas. Such as Lady
Finger (Abelmoschus esculentus) is known by Bhindi , Gumbo in
different countries.To solve out the confusion
occurred by the common names of some organisms.
Such as Silver fish , Cuttle fish are example of arthropods and molluscs respectively , but the name produce confusion that they belong to class Pisces.
How to write scientific namesCarlous Linnaeus introduced the
system of providing unique names to each organism.
Few rules are proposed for naming that are following :
1.Name should be given in Latin language.
2. Name of Genus begins with capital letter.
3.Name of the species begins with small letter.
4.The scientific name should be written in italics when printed and should be underlined separately
when hand written.Such as the name for Humans is
Homo sapiens for Lion is Panthera Leo.