Chapter 3, Problem 20P

A rooster with a particular comb morphology called walnut was crossed to a hen with a type of comb morphology known as single. The F₁ progeny all had walnut combs. When F males and females were crossed to each other, 93 walnut and 11 single combs were seen among the F progeny, but there were also 29 birds with a new kind of comb called rose and 32 birds with another new comb type called pea.

a. Explain how comb morphology is inherited.

b. What progeny would result from crossing a homozygous rose-combed hen with a homozygous pea-combed rooster? What phenotypes and ratios would be seen in the F2 progeny?

c. A particular walnut rooster was crossed to a pea hen, and the progeny consisted of 12 walnut, 11 pea, 3 rose, and 4 single chickens. What are the likely genotypes of the parents

d. A different walnut rooster was crossed to a rose hen, and all the progeny were walnut. What are the possible genotypes of the parents?