Polydactyly is a dominant trait. A male who has polydactyly would be represented by what symbol on a pedigree chart?
A) a half-shaded square
B) a shaded square
C) a half-shaded circle
D) a clear circle

Question

Quizplus · Accepted Answer

A male with polydactyly is affected by the trait, which is represented by a shaded square on a pedigree chart. Since polydactyly is a dominant trait, only one copy of the allele is required to express the trait, making it fully penetrant. Therefore, the square is shaded to indicate that the individual has the trait.

Polydactyly Is a Dominant Trait