Sex-linked diseases are more likely to afflict sons of female carriers because
A) males inherit two X chromosomes from their mothers.
B) males have only one X sex chromosome.
C) sex-linked disorders are recessive in fathers.
D) it is carried only on the Y chromosome.

Question

Quizplus · Accepted Answer

Males have only one X chromosome (inherited from their mother) and one Y chromosome (inherited from their father). Since many sex-linked diseases are recessive and located on the X chromosome, a male only needs to inherit one affected X chromosome to express the disease, whereas females, with two X chromosomes, would need to inherit two affected copies to express the disease.

Sex-Linked Diseases Are More Likely to Afflict Sons of Female