Two pure-breeding mutant plants produce white flowers. When they are crossed, all of the progeny have wild-type purple flowers. What does this genetic complementation tell you?
A)The genes are part of distinct biosynthetic pathways.
B)The two lines exhibit different mutations in the same gene.
C)More than one gene is involved in determining the phenotype.
D)The allele is pleiotropic.
E)The allele exhibits incomplete dominance.

Question

Quizplus · Accepted Answer

The fact that the progeny exhibit a wild-type phenotype indicates that both parents had mutations in different genes involved in the same pathway, and that the normal function was restored in the progeny by complementation. If the two lines exhibited different mutations in the same gene, the progeny would still have a mutant phenotype. The presence of a single allele with incomplete dominance or pleiotropic effects would result in an intermediate or altered phenotype, respectively, in the progeny.

Two Pure-Breeding Mutant Plants Produce White Flowers