Question

A man who has an X-linked recessive allele ...

cannot pass it down to his daughters.

always expresses the recessive phenotype.

is a carrier, with the recessive phenotype hidden.

inherited it from his father. All of the above are true.

Answer 1

X-linked recessive disorder are more common in male rather than female. Male has only one X chromosome so male get affected by the presence of just one X chromosome while if female having the mutation or genes in both the X chromosome then female will be affected. If the mutation is present in only one X chromosome then they are considered as carrier.

A man with X-linked recessive allele can pass it down to his daughters but if their mother is normal then the daughters will be only carrier. Man with X-linked recessive allele are affected not carrier.

It always expresses the recessive phenotype.