At first, a mutation may make no difference to an individual. Even if the mutation results in a nonfunctional protein, the body's cell may have a functional copy of the gene as its second allele. However, this new
nonfunctioning version could be passed on as a recessive allele. This kind of mutation is the probable origin of many
recessive disorders. Only characteristics that are expressed can be targets of natural selection. Therefore, natural
selecti CANNOT operate against recessive alleles, even if they are unfavorable. What does this explain?
a. why natural selection can only act against heterozygous carriers of a recessive disorder
b. why genetic disorders can persist in a population
c. why advantageous offspring are more likely to survive and reproduce
d. why recessive alleles are never expresses