DIVERSITY IN LIVING ORGANISMS CLASS 9 BIOLOGY

DIVERSITY IN LIVING ORGANISMS CLASS 9 BIOLOGY

Monkey and Human

Desi cow and Jersey cow

Difference in size Bacteria = few micrometre Blue whale = 30 metre Redwood tree of California = 100 metre

Look for similarities … • We have a bewildering variety of life around us and very less time to understand all living organisms. • We can put organisms into different classes by looking for similarities and study that class or group as a whole.

Make groups and sub groups • Decide which characteristics decide more fundamental differences among organisms. • This would create the main broad group. • Smaller sub groups would be created by less important characteristics.

Aristotle – a Greek thinker

Basis of classification by Aristotle • Classification of animals on the basis of whether they live on land, water or air. (difference in habitats) • This classification is misleading. Example: Corals, whales, octopuses, starfish and sharks only have their habitat in common (aquatic). Other features are uncommon.

Characteristics • A distinct or peculiar feature or quality. • A particular form or function , i.e ,the details of appearance or behaviour.

Some characteristics used for classification or grouping… • Eukaryotic and prokaryotic cell • Unicellular and multicellular organisms • Presence and absence of photosynthesis • Presence and absence of division of labour and specialized organs • Difference in basic body design of plants and animals

Role of time… • Characteristics that come into existence earlier are more basic than characteristics that have come into existence later. • Organisms which have occurred earlier and are simpler are the older organisms and those which are new and more complex are younger organisms.

Evolution • Most life forms that we see today have arisen by an accumulation of changes in body design that allow the organism possessing them to survive better. • Primitive or Lower organisms – Organisms with ancient body design that have not changed much. • Advanced or Higher organisms – Organisms which have attained their body design relatively recently.

BIO DIVERSITY • This word was coined by Walter G.Rosen. • Biodiversity is the occurrence of diverse or varied forms of living beings, which differ from each other in external appearance, size, colour pattern, internal structure, nutrition, behaviour, habitat etc. • Diverse life forms share the environment and are affected by each other too. Hence a stable community of different species comes into existence.

Region of Mega diversity • Warm and humid tropical regions of Earth between tropic of cancer and tropic of Capricorn.

Some biologists who classified organisms… • Ernst Haeckel (1894) • Robert Whittaker (1959) • Carl Woese (1977) • They tried to classify organisms into broad categories called kingdoms.

Whittaker’s 5 kingdom classification Basis of classification • Cell structure • Mode of nutrition • Source of nutrition • Body organisation

Whittaker’s 5 Kingdoms • Monera • Protista • Fungi • Plantae • Animalia

Carl woese • He modified 5 kingdom classification by further sub dividing Kingdom Monera into – • Archaebacteria (or Archaea) • Eubacteria (or Bacteria)

Different mutually related groups are made based on various characteristics. Basic unit of classification is species. HIERARCHY OF CLASSIFICATION

HIERARCHY OF CLASSIFICATION • Species – Group of individuals with similar morphological characters, which are able to breed among themselves and produce fertile off springs of their own kind. • Genus – It is a group of species which are related and have less characters in common as compared to species. They have identical reproductive organs. • Family – A group of related genera that are more similar to each other than with the genera of other families. • Order – It is an assemblage of families resembling one another in a few characters. • Class – It represents organisms of related orders. • Phylum – It includes all organisms belonging to different classes having a few common characters. • Kingdom – It includes all organisms that share a set of distinguishing common characters.

Characteristics of 5 kingdom classification of Whittaker MONERA • No well defined nucleus • Unicellular • Some have a cell wall and some don’t. • Some are autotrophic and some are heterotrophic. • Bacteria, Blue green algae or Cyanobacteria (Anabaena) , Mycoplasma

Continued… PROTISTA • Unicellular • Eukaryotic • Move using hair like cilia or whip like flagella • Either autotrophic or heterotrophic mode of nutrition. • Unicellular algae, diatoms, protozoans ( Paramecium, Amoeba, Euglena)

Continued… FUNGI • Heterotrophic • Eukaryotic • Saprophytes – use decaying organic matter as food • Cell wall made of tough complex sugar called Chitin. • Can become multicellular at certain stages in their lives. • Yeast, mushrooms (Agaricus) , Aspergillus, Penicillium,

Continued… PLANTAE • Multicellular • Eukaryotes • Have cell wall • Autotrophic nutrition- have chlorophyll, show photosynthesis

Continued… ANIMALIA • Multicellular • Eukaryotes • No cell wall • Heterotrophic mode of nutrition (can not perform photosynthesis)

DIVERSITY IN LIVING ORGANISMS CLASS 9 BIOLOGY