SUMMARY

The living world is rich in variety. Millions of plants and animals have been identified and described but a large number still remains unknown. The very range of organisms in terms of size, colour, habitat, physiological and morphological features make us seek the defining characteristics of living organisms. In order to facilitate the study of kinds and diversity of organisms, biologists have evolved certain rules and principles for identification, nomenclature and classification of organisms. The branch of knowledge dealing with these aspects is referred to as taxonomy. The taxonomic studies of various species of plants and animals are useful in agriculture, forestry, industry and in general for knowing our bio-resources and their diversity. The basics of taxonomy like identification, naming and classification of organisms are universally evolved under international codes. Based on the resemblances and distinct differences, each organism is identified and assigned a correct scientific/biological name comprising two words as per the binomial system of nomenclature. An organism represents/occupies a place or position in the system of classification. There are many categories/ranks and are generally referred to as taxonomic categories or taxa. All the categories constitute a taxonomic hierarchy.

Taxonomists have developed a variety of taxonomic aids to facilitate identification, naming and classification of organisms. These studies are carried out from the actual specimens which are collected from the field and preserved as referrals in the form of herbaria, museums and in botanical gardens and zoological parks. It requires special techniques for collection and preservation of specimens in herbaria and museums. Live specimens, on the other hand, of plants and animals, are found in botanical gardens or in zoological parks. Taxonomists also prepare and disseminate information through manuals and monographs for further taxonomic studies. Taxonomic keys are tools that help in identification based on characteristics.

EXERCISES

1. Why are living organisms classified?

2. Why are the classification systems changing every now and then?

3. What different criteria would you choose to classify people that you meet often?

4. What do we learn from identification of individuals and populations?

5. Given below is the scientific name of Mango. Identify the correctly written name.

Mangifera Indica / Mangifera indica

6. Define a taxon. Give some examples of taxa at different hierarchical levels.

7. Can you identify the correct sequence of taxonomical categories?

(a) Species - Order - Phylum - Kingdom

(b) Genus - Species - Order - Kingdom

(c) Species - Genus - Order - Phylum

8. Try to collect all the currently accepted meanings for the word ‘species’. Discuss with your teacher the meaning of species in case of higher plants and animals on one hand, and bacteria on the other hand.

9. Define and understand the following terms: (i) Phylum (ii) Class (iii) Family (iv) Order (v) Genus

10. How is a key helpful in the identification and classification of an organism?

11. Illustrate the taxonomical hierarchy with suitable examples of a plant and an animal.