[Campbell Biology P.348] Why are X-linked recessive disorders far more common in males than ... | Practice Question

Why are X-linked recessive disorders far more common in males than in females?

  • A: The Y chromosome carries dominant alleles that mask the X-linked recessive traits.
  • B: Fathers pass X-linked recessive alleles to all of their sons.
  • C: Males have only one X chromosome, so any recessive allele on it will be expressed.
  • D: The recessive alleles are more likely to mutate in males.

Explanation

The text states that because males have only one locus for an X-linked gene a condition called hemizygous , a single recessive allele is sufficient to be expressed. Females, having two X chromosomes, would need two copies of the recessive allele to express the trait, which is a much less probable event.