Chapter 4, Problem 5P

In a type of parakeet known as a “budgie,” feather color is controlled by two genes. A yellow pigment is synthesized under the control of a dominant allele Y. Budgies that are homozygous for the recessive y allele do not synthesize yellow pigment. At an independently assorting gene, the dominant allele B directs synthesis of a blue pigment. Recessive homozygotes with the bb genotype do not produce blue pigment. Budgies that produce both yellow and blue pigments have green feathers; those that produce only yellow pigment or only blue pigment have yellow or blue feathers, respectively; and budgies that produce neither pigment are white (albino).

a. List the genotypes for green, yellow, blue, and albino budgies.

b. A cross is made between a pure-breeding green budgie and a pure-breeding albino budgie. What are the genotypes of the parent birds?

c. What are the genotype(s) and phenotype(s) of the $\text{F1}$ progeny of the cross described in part (b)?

d. If $\text{F1}$ males and females are mated, what phenotypes are expected in the $\text{F2}$, and in what proportions?

e. The cross of a green budgie and a yellow budgie produces offspring that are $\text{12}$ green, $\text{4}$ blue, $\text{13}$ yellow, and $\text{3}$ albino. What are the genotypes of the parents?