Question 1
Gene interactions in which an allele of one gene modifies or prevents expression of alleles of another gene is known as ________.
◦ pleiotropy
◦ incomplete dominance
◦ codominance
◦ epistasis
◦ incomplete penetrance
Question 2
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?
◦ The bearded billy goat must be heterozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.
◦ Both the bearded billy goat and beardless female must be heterozygous for the bearded allele.
◦ The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be heterozygous for the bearded allele.
◦ Both the bearded billy goat and beardless female must be homozygous for the bearded allele.
◦ The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.
Continuous variation in a polygenic trait.
Ancestral versus shared derived characters involving a molecular trait.
Female choice based on male appearance.
A pedigree showing the inheritance of a trait through several generations of a family.
A pedigree for an autosomal dominant trait
Disruptive selection eliminates midrange forms of a trait