In certain goat breeds, appearance of a chin beard is a sex- influenced trait. Recall that bearding is inherited as an autosomal trait determined by two alleles, B1 and B2, and females must be homozygous for the bearded allele, B2, to have a beard. What genotypes must a bearded billy goat (male) and a beardless female goat have if they have a bearded female offspring?
A) The bearded billy goat must be heterozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.
B) The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.
C) Both the bearded billy goat and beardless female must be heterozygous for the bearded allele.
D) The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be heterozygous for the bearded allele.
E) Both the bearded billy goat and beardless female must be homozygous for the bearded allele.

Question

Quizplus · Accepted Answer

For a bearded female offspring to occur, she must inherit a bearded allele (B2) from both parents. Since the female is beardless, she cannot be homozygous for the bearded allele (B2B2) as stated in the question, but must carry one bearded allele to pass to her offspring, making her heterozygous (B1B2). The bearded billy goat can be either heterozygous (B1B2) or homozygous (B2B2) for the bearded allele to pass it on.

In Certain Goat Breeds, Appearance of a Chin Beard Is