Four Marks Questions

1. Define species. Explain the various aspects of species?

A: 'Species is an interbreeding group of similar individuals, sharing the common gene pool and producing fertile offspring'. - Buffon Species is the basic unit of classification. Species is a latin word meaning 'kind' or 'appearance'. John Ray in his book Historia Generalis Plantarum used the term 'species' and described it on the basis of common descent (origin from the ancestors) as a group of morphologically similar organisms. Linnaeus considered species in his book Systema Naturae as basic unit of classification. Buffon, in his book Natural History, proposed the idea of evolution of species which is the foundation for the biological concept of evolution. Charles Darwin, in his book The Origin of species. Species is a dynamic nature. Species is considered a group of individuals, which are:

i) Reproductively isolated from individuals of other species - A breading unit.

ii) Sharing the same ecological niche - An ecological unit.

iii) Showing similarity in the kanyotype - A genetic unit.

iv) Having similar structure and functional characteristics - An evolutionary unit.

2. What are the reasons for the greater biodiversity in the tropics?

A: Reasons:

‣ Tropical latitudes have remained relatively undisturbed for millions of years. Thus had a long 'evolutionary time'. As long duration was available in this region for speciation. It led the species diversification.

‣ Tropical climates are relatively more constant and predictable than that of this temperate regions. Constant environment promotes niche specialization.

‣ Solar energy, resources like water etc., are available in abundance in this region. This contributed to higher productivity. In terms of food, production, leading to greater diversity.

Two Marks Questions

1. What is trinominal nomenclature? Give an example?

A: It is the extension of the binominal nomenclature. This system permits the designation of subspecies with a three-worded name called trinomen nomenclature.

e.g: Human: Homo sapiens sapiens,

Crow: Corvus splendens splendens.

2. What is meant by tautonymy? Give two examples.

A: The practice of naming the animals, in which the generic and species name are the same, is called 'tautonymy'. So the name is called tautonym. e.g.: Axis axis - Spotted deer, The Indian

cobra - Naja naja

3. What does ICZN stands for?

A: ICZN - International code of Zoological Nomenclature.

4. Write the full form of IUCN. In which book threatened species are enlisted?

A: IUCN - International Union for the Conservation of nature and Natural resources. Threatened species are listed in the 'Red Data Books'.