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 attached earlobes? A. He has no recessive alleles. B. He has a homozygous genotype. C. He has a heterozygous genotype. D. He has one of each allele.

Answer 1

A boy with attached earlobes must have two copies of the recessive allele, making his genotype homozygous recessive (ee), which explains why he expresses this recessive trait.

Step-by-step explanation:

If a boy is born with attached earlobes, the correct statement is B. He has a homozygous genotype. Attached earlobes are a recessive trait; to express this trait, he must have two copies of the recessive allele (ee). Since the dominant allele for detached earlobes (E) is not present, he cannot have a heterozygous genotype (Ee) because in that case, the dominant trait of detached earlobes would be expressed.