Dihybrid crosses can be conducted with two organisms that are heterozygous for two different traits: SsYy x SsYy for example. Which genotypic ratio shows that genes in dihybrid crosses are inherited according to the principle of independent assortment?

Question

A.

25:25:25:25

B.

50:50

C.

3:1

D.

9:3:3:1

Answer 1

The correct answer is D. 9:3:3:1.

In a dihybrid cross like SsYy x SsYy, where each parent is heterozygous for two traits, the offspring exhibit a phenotypic ratio of 9:3:3:1. This ratio demonstrates that the genes for the two traits assort independently of one another, consistent with Mendel's principle of independent assortment. The genotypic ratio would also show a similar distribution reflecting the combinations of the alleles.