In fruit flies, brown eyes can be caused by the recessive mutations pn (prune), bw (brown) or ry (rosy), which are on the X chromosome, second chromosome, and third chromosome, respectively.Wild-type alleles for all three genes must be present for eyes to be red.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

The brown-eyed sons indicate that the mutation is on the X chromosome, as they inherit their X chromosome from their mother. Therefore, the mutation responsible is pn (prune), which is X-linked.

In Fruit Flies, Brown Eyes Can Be Caused by the Recessive