Polydactyly is a dominant trait that results in extra fingers and toes in humans.A man with polydactyly marries a woman with 10 fingers and toes.They have a child that has a normal number of digits.The phenotype of the man's father is unknown,but his mother has a normal phenotype.What are the genotypes of the married couple? (D = polydactyl allele;d = wild type allele)
A)woman Dd,man dd
B)woman DD,man dd
C)woman dd,man DD
D)woman dd,man Dd
E)woman DD,man Dd or dd

Question

Quizplus · Accepted Answer

The man has polydactyly, so he must have at least one copy of the D allele. Since he only passes on a normal allele to his child, he must have two copies of the wild-type allele (dd). The woman has a normal phenotype, so she must have two copies of the wild-type allele (dd). Therefore, the woman is dd and the man is Dd. The grandfather's genotype is unknown, so it cannot be used to determine the genotype of the man.

Polydactyly Is a Dominant Trait That Results in Extra Fingers