Assume that a dihybrid cross is made in which the genes' loci are autosomal,independently assorting,and incompletely dominant.How many different phenotypes are expected in the offspring?
A)6
B)4
C)2
D)12
E)9

Question

Quizplus · Accepted Answer

In a dihybrid cross with independently assorting, incompletely dominant genes, each gene pair can produce three phenotypes (1:2:1 ratio for each gene). When you cross these, you get a 9:3:3:1 ratio, but because of incomplete dominance, each of the original Mendelian categories can split further based on the blending of traits. This results in more than the typical 4 phenotypes seen in a complete dominance scenario. However, the question asks for the total number of different phenotypes, not the ratio in which they appear. With two genes each able to produce three phenotypes due to incomplete dominance, the total number of phenotype combinations is 3 (from the first gene) x 3 (from the second gene) = 9 different phenotypes.

Assume That a Dihybrid Cross Is Made in Which the Genes