Notes on NCERT Chapter = 7 (DIVERSITY IN LIVING ORGANISMS) Part 1 => 9th class

This is Online Notes on NCERT  Chapter =   7 (DIVERSITY IN LIVING ORGANISMS) Part 1 of 9th class for preparation of CBSE BOARD Examination, NTSE etc.



CHAPTER AT A GLANCE:

All living organism are grouped on the basis of their similarities and increasing complexities into different complexities.

FIVE KINGDOM CLASSIFICATIONS:

Biodiversity means the variety of living organisms present on a particular region. 

There are about 20 lac organisms known on the earth which differ from one another in external form, internal structure, mode of nutrition, habitat, etc.

Taxonomy : It is a branch of biology which deals with identification, nomenclature and classification of organisms. Carolus Lannaeus is called the father of taxonomy.

Classification : The method of arranging organisms into groups or sets on the basis of similarities and differences is called classification.

Importance of Classification:

• It makes the study of wide variety of organisms easy and in systematic manner.
• It helps to understand how the different organisms have evolved with time.
• It helps to understand the inter-relationships among different groups of organisms.
• It forms a base for the study of other biological sciences, like biogeography.

Basis of Classification:

• There are certain features or properties used for the classification of living organisms which are known as characteristics. Organisms with same characteristics are placed in same groups.

Classification System:

• 1. Two kingdom classification : Carolus Linnaeus in 1758 classified the living organisms into two groups as plants and animals.
• 2. Five kingdom classification : H. Whittaker in 1959 further classified the organisms into five kingdoms as Kingdom Monera, Kingdom Protista, Kingdom Fungi, Kingdom Plantae and Kingdom Animalia.

[ Note : Carl Woese in 1977 further divided Kingdom Monera into
archaebacteria (or Archae) and Eubacteria (or Bacteria). ]

Hierarchy of Classification : 

Linnaeus proposed a classification system by arranging organisms into taxonomic groups at different levels according to the characteristics they have. The groups or the levels from top to bottom are :

The major characteristics considered for classifying all organisms into five ajor kingdoms are :

• Type of cellular organization:

(a) Prokaryotic cells : These are primitive and incomplete cells without well-defined nucleus.

(b) Eukaryotic cells : These are advanced and complete cells with well defined nucleus.

• Body organization:

(a) Unicellular organisms : These are organisms made up of single cell with all activities performed by the single cell.

(b) Multicellular organisms : These are organisms made up of large number of cells with different functions performed by different cells.

• Mode of obtaining food:

(a) Autotrophs : These are the organisms that make their own food by photosynthesis.

(b) Heterotrophs : These are the organisms which depend on other
organisms for food.

Nomenclature : An organism can have different names in different
languages. This creates confusion in naming organism. A scientific name is needed which is same in all languages. Binomial nomenclature system given by Carolus Linnaeus is used naming different organisms.

Following are some conventions in writing the scientific names :

(1) Genus should be written followed by the species.
(2) First letter of the genus should be capital and that of the species should be in small letter.
(3) When printed the name should be written in italics and when written with hands genus and species should underlined separately.

Example : Homo sapiens for humans, Panthera tigris for tiger.

Kingdom I : MONERA

(i) Prokaryotic, unicellular.
(ii) Can be autotrophs or heterotrophs.
(iii) May or may not have cell wall.
(iv) Examples : Anabaena and Bacteria (heterotrophic), Cyano-bacteria or Blue-green algae (autotrophic).

Kingdom II : PROTISTA

(i) Eukaryotic, unicellular.
(ii) Can be autotrophic or heterotrophic.
(iii) May have cilia, flagella or pseudophodia for locomotion.
(iv) Examples : Plants like unicellular algae, diatoms; animals like protozoans (Amoeba, Paramecium, Euglena); fungi like slime molds and water molds.

Kingdom III : FUNGI

(i) Eukaryotic.

(ii) Mostly multicellular but sometimes unicellular (yeast).

(iii) Source of food :

(a) Mostly saprophytes : These organisms use decaying material for food.

(b) Some parasitic : These organisms live inside body of other living organism to have food and can be disease causing.

(c) Symbiotic relation : These are relations between two organisms in which they live together for benefit of one or both. Lichens are a symbiotic relation between fungi and cyanobacteria. Here fungi gets food from cyanobacteria and in return cyanobacteria gets water and protection from sunlight through fungi.

(iv) Cell wall is made of chitin.

(v) Examples : Mushrooms (Agaricus), green mold (Penicillium), smut (Aspergilus).

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