Dec 13

A nectarine is a peach without fuzz. That difference is controlled by a single gene with two alleles, D and d. Which (peach or nectarine) is likely to be homozygous for the recessive allele (d)? Why?

One would assume that the nectarine (without fuzz) has the recessive allele.

Loss of function mutants tend to be recessive, because they are not making something that is normally made. A single normal allele can usually provide the necessary product or signal.