In fruit flies, brown eyes can be caused by recessive mutant alleles of any one of three genes: pn (prune), bw (brown)or ry (rosy).The pn gene is X-linked, bw is on the second chromosome, and ry is on the third chromosome.One wild-type allele of each of the three genes must be present for eyes to be red (wild type).Suppose that two brown-eyed flies are crossed and their progeny consist of brown-eyed sons and red-eyed daughters.Which mutation is responsible for the brown eyes in the parental female?
A)pn
B)bw
C)ry
D)either bw or ry
E)any of the three-pn, bw, or ry

Question

Quizplus · Accepted Answer

Since the progeny consists of brown-eyed sons and red-eyed daughters, the mutation causing brown eyes in the parental female must be X-linked. The pn gene is the only one of the three that is X-linked, which explains the observed inheritance pattern.

In Fruit Flies, Brown Eyes Can Be Caused by Recessive