Question

why are more males than females affected by x - linked recessive genetic diseases?
females have two y chromosomes and cannot be affected by x - linked traits.
males and females are affected equally by x - linked recessive genetic conditions.
females have an additional y chromosome to mask the x - linked recessive allele.
females have no y chromosome to mask the x - linked recessive allele.
males have a y chromosome that cannot mask the x - linked recessive allele.

Explanation:

• Females have two X chromosomes (XX), so if one X has a recessive allele, the other X may have a dominant allele to mask it.
• Males have one X and one Y chromosome (XY). The Y chromosome does not carry alleles to mask X - linked recessive alleles on the X chromosome.

Answer:

Males have a Y chromosome that cannot mask the X - linked recessive allele.