A person resembles his grandfather, a girl seems to be a photocopy of her aunt, generally we hear such comments. These similarities are the result of inherited traits transmitted from parent to progeny.

According to Mendel traits like the colour of seed, seed coat, length of stem etc. were heritable traits from parental generation. Transmission or passing of characters or traits from parent to offsprings is called 'Heredity'.

The process in which Traits are passed from one generation to another generation is called 'Inheritance'.

Mendel hypothesised that each character or trait is expressed due to a pair of factors or 'alleles' (contrasting expressions of the same trait), as he named them. Now we know that these are known as 'genes'. Gene is a segment of a nucleic acid called 'DNA' which is present in the nucleus of every cell. It controls the expression of a trait or character. In viruses RNA can also be controlling the expression of a characte