With independent assortment, the ratio of phenotypes in the F₂ generation of a cross between true-breeding strains (AA bb × aa BB) can be described as 9:3:3:1 when A and B are dominant over a and b. To what phenotype does the "9" in the ratio refer? A)recessive for both traits B)dominant for the A trait and recessive for the B trait C)dominant for one trait and recessive for the other D)dominant for both traits

Question

Quizplus · Accepted Answer

The 9 in the ratio refers to the phenotype that is dominant for both traits (AA BB). This is because when two true-breeding parents with different homozygous genotypes for two traits are crossed, the F1 generation will be heterozygous for both traits, and in the F2 generation, the dominant phenotype for both traits will appear in a 9:3:3:1 ratio due to independent assortment of alleles.

With Independent Assortment, the Ratio of Phenotypes in the F2

With Independent Assortment, the Ratio of Phenotypes in the F₂