Question

How many types of pollen grains are formed by dihybrid plants?

• A. One
• B. Two
• C. Four
• D. Eight

Answer 1

Answer: (C)

Total number of types of gamete produce by an organism is 2${}^n$, where n is the number of heterozygous genes present. As we know that dihybrid plant, for example AaBb, is heterozygous for two genes, thus total possible gametes by it = 2${}^2$ = 4. Option C is correct.

A trihybrid plant, for example AaBbCc, is heterozygous for three genes, thus total possible gametes by it = 2${}^3$ = 8 which makes option D wrong. If aplant is heterozygous for single gene, for example Aa, thus total possible gametes by it = 2${}^1$ = 2 which makes option B wrong. Single type of gamete is produced by homozygous plants, for example AA, BB etc.