(a) What is meant by 'heredity' ? What are the units of heredity.

(b) State Mendel's first law of inheritance.

(a) The transmission of characters from parents to the offspring’s is called heredity. The units of heredity are genes.
(b) According to Mendel’s first law of inheritance: The characteristics (or traits) of an organism are determined by internal ‘factors’ which occur in pairs. Only one of a pair of such factors can be present in a single gamete