Wild type rats have grey coats. The recessive allele r causes yellow coat color, while an unlinked recessive allele a of another gene cause black coats. Rats homozygous for both a and r have white coats.

a) If pure-breeding yellow and black rats are crossed, what phenotypes are expected in the F1?

b) If the F1 interbreed, what types of F2 are expected and in what ratios?

c) A grey rat from the F2 produced yellow, black, grey, and white progeny when bred with a white female, but only black or grey when bred with true-breeding black females. What was its genotype?

d) An F2 yellow rat was bred with an F2 black rat. They produced a total of 3 grey, 2 yellow, 1 black, and 1 white offspring. What was the genotype of these two F2 rats?