Question

Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the white progeny?A) A_ B_B) A_ bbC) aa B_D) aa bb *Correct answerE) A_ B_ and A_ bb

Answer 1

Answer:

D) aa bb

Explanation:

Whenever there are two loci involved in a certain trait and after a cross the phenotypic ratio of the offspring is 12:3:1 (instead of the expected 9:3:3:1) there is dominant epistasis, where the presence of a dominant allele in one locus masks the expression of the other locus. In this case, for loci A and B, we could say that the offspring have the following genotypes:

• 9 A_B_ : pink
• 3 A_bb : pink
• 3 aaB_: black
• 1 aabb: white

The presence of the dominant allele A in the A/a locus gives pink coat color, regardless of the alleles in the B/b locus.