Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow.
-What type of gene interaction does this represent?
A) recessive epistasis
B) dominant epistasis
C) duplicate recessive epistasis
D) duplicate dominant epistasis
E) dominant and recessive epistasis

Question

Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. 
-What type of gene interaction does this represent?
A) recessive epistasis
B) dominant epistasis
C) duplicate recessive epistasis
D) duplicate dominant epistasis
E) dominant and recessive epistasis

Quizplus · Accepted Answer

This represents recessive epistasis because the presence of two recessive alleles (ee) at the E locus masks the expression of the alleles at the B locus, resulting in yellow hair regardless of whether the B locus has alleles for black or brown pigment.

Hair Color Is Determined in Labrador Retrievers by Alleles at the B