Question

Earlobes can be either attached or detached. The allele for attached earlobes is recessive (

e., and the allele for detached earlobes is dominant (
e. What must be true if a boy is born with detached earlobes?

Answer 1

If the allele for attached earlobes is recessive and the allele for detached earlobes is dominant and a boy is born with detached earlobes; then he must carry in his genes an allele for detached earlobes which is dominant while also carrying an allele for attached earlobes that is recessive. Although his genotype carries both alleles, it's the detached earlobe that is expressed on his phenotype side.