Question

How many types and in what ratio the gametes are produced by a dihybrid heterozygous?

• A. 4 types in the ratio of 9:3:3:1
• B. 2 types in the ratio of 3:1
• C. 3 types in the ratio of 1:2:1
• D. 4 types in the ratio of 1:1:1:1

Answer 1

The correct option is D 4 types in the ratio of 1:1:1:1

The cross between two homozygous parents considering two pairs of contrasting alleles is called as dihybrid cross e.g., YYRR (yellow and round ) is crossed with yyrr (green and wrinkled). The gametes formed are YR and yr. After fertilisation, the F1 heterozygote will be formed i.e YyRr (yellow and round). On selfing F1 we get two possible combinations i.e YR, Yr, yR, yr. Therefore four types of gametes are formed in the ratio of 1:1:1:1. Thus, the correct answer is option D.