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? A. 25:25:25:25 B. 50:50 C. 3:1 D. 9:3:3:1

Answer 1

In a dihybrid cross involving two heterozygous organisms, such as SsYy x SsYy, the principle of independent assortment predicts that the alleles for each gene segregate independently. The expected genotypic ratio for such a cross is 9:3:3:1. This means there will be nine combinations of both dominant traits, three combinations of one dominant and one recessive trait, three combinations of the other dominant and the recessive trait, and one combination of both recessive traits.

Therefore, the correct answer is D. 9:3:3:1.