NEET Biology Diversity In The Living World Revision Notes

Nomenclature is to provide a scientific name for every living organism to be followed al over the world. This will avoid, conferring different names to the same organism in different part of the world and in differe4nt languages for e.g., a dog is called 'kutta' in Tamil and these names are not understood elsewhere.

 

Nomenclature is a system of naming plants and animals and in biology every organism is given two names. The first is the name f the genus (generic name) and second is the name of the species (specific name). The generic name is shared by a number of other closely related organisms. (It is like sharing the surname with other members of thesame family) whereas the second name species is possessed only by one kind of organism in the genus (not shared with any other organism n the genus). It is a convention that generic name is followed by the specific name and have Latin endings. e.g., the scientific name of human being is Homo (generic) sapiens (specific). Thus this type of naming each organism is bionmial nomenclature which was first developed and used by Linnaeus who has been considered as Father of taxonomy. He published his book Species plantarum in 1753. Thus the scientific names are unique, understood and followed all over the world and are not changed easily and they are guided by a set of rules stated in International code of Nomenclature.Hence giving a Latin name to a living organism is not enough, unless it is grouped or placed in a system which relates it to all other living things, which is done by arranging al organisms into groups called tax, which is further split into smaller groups, with each group having certain common features. Living organisms are first grouped into plant and animal kingdom which are further split into smaller group such as phyla, and phyla into classes, classes into order into families, families into genera and genera into species. Thus species is the basic level of all latest classification. (Species is an isolated reproductive unit, group of similar organisms that are able to breed together and produce fertile offspring). (e.g. Human beings, dogs etc.) if two different species inter-breed, the product is sterile (e.g., horse x sterile mule).

 

The differences between plants and animals are distinct, plants are stationary, trap solar energy and synthesize their own food and grow and some grow indefinitely, whereas animals generally move, consume plants or other animals and their body stops growing after attaining certain size. The plants cells have a cell wall and contain chloroplast synthesize starch whereas animal cells neither have cell wall nor chloroplast. Based on these basic differences the plants and animals are grouped into two groups namely Plant kingdom and Animal kingdom. This system of classification was first purposed by Carlus Linnaeus in 1758. But further taxonomic studies indicated that certain organisms could not be placed in ether of the above groups because of certain unique characters. Hence a German Zoologist, E.H. Haeckel (1866) raised a third kingdom Protista for unicicellular organisms. But when significant differences become evident among the protists, an American ecologist Robert H. Whittaker (1969) proposed a fourth kingdom monera for bacteria which are prokaryotes and fifth one, kingdom Fungi, whose members are eukaryotic, lack chlorophyll and obtain their food through obsorption. Thus Classification of organism is a