Mouse pigmentation is subject to epistasis of the B alleles by the d alleles. B (black) is dominant over b (brown), and D is dominant over d . Homozygous d is epistatic to the black and brown genes. Given this information, what genotype(s) result in a white mouse (no pigment)?
A) BBdd only
B) Bbdd only
C) bbDD only
D) bbDd only
E) BBdd and Bbdd

Question

Quizplus · Accepted Answer

The presence of homozygous recessive dd genotype is necessary for a mouse to be white, regardless of the B allele configuration. This is because the d allele is epistatic to both B and b alleles, meaning it can mask their effects when in the homozygous recessive form. Therefore, both BBdd and Bbdd genotypes result in a white mouse.

Mouse Pigmentation Is Subject to Epistasis of the B Alleles