In Drosophila, production of eye color pigment requires a functional protein encoded by the white locus.Individuals with two copies of the w allele lack any eye color pigment; individuals with at least one wild-type allele have pigment.The bw allele at the brown locus produces a defective enzyme responsible for converting one type of pigment to another.Individuals with two bw alleles have brown eyes; individuals with at least one wild-type allele at the brown locus have normal red eyes (assuming that they have eye pigment).Which statement is true?
A) bw is dominant to w.
B) w is dominant to bw.
C) The white locus is epistatic to (affects the expression of) the brown locus.
D) The brown locus is epistatic to (affects the expression of) the white locus.
E) bw and w are codominant.

Question

Quizplus · Accepted Answer

The white locus is epistatic to the brown locus because the presence of the w allele (which results in no eye pigment) will mask the effect of the bw allele at the brown locus, meaning the color alteration from brown to red cannot occur without pigment produced by the white locus.

In Drosophila, Production of Eye Color Pigment Requires a Functional