Explain the terms: Monohybrid cross, Dihybrid cross, Monohybrid ratio and Dihybrid ratio.

Monohybrid cross: Monohybrid cross is that cross which is made to study the inheritance of a single pair of genes or factors of a character.

Dihybrid cross: It is a cross which involves the study of two pairs of genes or two characters.

Monohybrid ratio: It is the ratio which is obtained in the F2 generation when a monohybrid cross is made. It is usually 3 : 1 (phenotypic ratio) or 1 : 2 : 1 (genotypic ratio).

Dihybrid Ratio: It is the ratio which is obtained in F2 generation when a dihybrid cross is studied. It is usually 9 : 3 : 3 : 1 (phenotypic ratio).