Index >> Genetics Introduction

In other words, we can say that each species has individuality, i.e., each species is recognisable by its certain specific morphological, physiological and behavioural characteristics. For example, each person has certain peculiar characteristics by which he is easily recognised by other persons. Similarly, the dogs of same breed are distinguishable from each other by certain structural differences. The characters which provide individuality to a species are said to cause variation among the species.
The characters which provide individuality to a species are said to cause variation among the species. The variations may be of following two kinds:
1. Hereditary variations-Among the sexually reproducing organisms no two individuals have the same heredity. The differences in the hereditary constitutions of the individuals of a species are known as hereditary or genetical variations.

Although most people associate genetics primarily with heredity, but there are some such as A. C. Paj, (1974) who prefers to consider science of genetics to be basically the study of life. Pal argues that besides heredity, many other life phenomena such as the capacity to reproduce, to evolve, to respond to stimuli and to carry out internal biochemical (i.e., metabolic) reactions, all of which characteristically differentiate a living organism from non-living matter, are in fact under genetic control.