Guinea pig coat color is determined by a single gene. The allele for black coat color is dominant to brown. In a cross between two black-haired guinea pigs, 20 offspring are born. If both parents were heterozygous, probability would predict that approximately how many of the 20 offspring would have brown hair?

Question

Guinea pig coat color is determined by a single gene. The allele for black coat color is dominant to brown. In a cross between two black-haired guinea pigs, 20 offspring are born. If both parents were heterozygous, probability would predict that approximately how many of the 20 offspring would have brown hair?

A.
15
B.
5
C.
10
D.
0

Answer 1

The allele for black coat color is dominant to brown. If both parents are heterozygous (Bb), the possible genotypes for their offspring are BB, Bb, and bb.

The probability of an offspring having brown hair (bb) is 25% (1 out of 4 possibilities) since it is recessive.

Therefore, out of the 20 offspring, approximately 5 would be expected to have brown hair.

Answer: B. 5