Recessive X-linked traits are more likely to be expressed in a male fruit fly than a female fruit fly because
A)males are haploid.
B)the male's phenotype results entirely from his single X-linked gene.
C)the male chromosome is more fragile than the female chromosome.
D)the male chromosome is more susceptible to mutations.

Question

Quizplus · Accepted Answer

In male fruit flies, there is only one X chromosome, so any recessive X-linked trait on that chromosome will be expressed in the phenotype. In contrast, female fruit flies have two X chromosomes, so the presence of a dominant allele on one of the X chromosomes can mask the expression of a recessive allele on the other X chromosome. Thus, recessive X-linked traits are more likely to be expressed in males than females. Choices A, C, and D are not accurate explanations for this phenomenon.

Recessive X-Linked Traits Are More Likely to Be Expressed in a Male