1. A dominant gene (A) causes yellow color in rats, the dominant allele on another independent gene (R) produces black coat color. When the two dominants occur together (A_ R_) they interact to produce gray coat color. Rats of the genotype aa are cream-colored. If a gray male and a yellow female, when mated, produce offspring approximately 3/8 of which are yellow, 3/8 gray and 1/8 cream, and 1/8 black, what are the genotypes of the parents

Parents: Yellow (Aarr) and Grey (AaRr)

Explanation:

Given:

allele A = yellow

allele R = black,

Heteroozygous = gray

Genotypes of the parents:

yellow (Aarr) - female

gray (AaRr) - gray

cross between these

Parents: Yellow (Aarr)  and Grey (AaRr)

Gametes: (Ar, ar) and (AR, Ar, aR, ar)

F1 (Punnet square)

| AR | Ar | aR | ar

Ar | AARr (gray) | AArr (yellow) | AaRr (gray) | Aarr (yellow)

ar | AaRr (gray) | Aarr (yellow) | aaRr (black) | aarr (cream)

Ratio: 3/8 yellow : 3/8 gray : 1/8 cream : 1/8 black