biology, genetics help, please...?

Question

In order for a female to be a hemophiliac, what must be said of her parents?

In order for a male to be a hemophiliac, what must be said of his parents?

please base your answers on genetic sex-linkage...

Answer 1

Hemophilia is a recessive allele located on the X chromosome.
A female with hemophilia must be XhXh, so she got the hemophilia allele from both parents. Her mother was most likely a carrier, XHXh, and her father had to have hemophilia, XhY.

A male with hemophilia had to get the allele from his mother since he got the Y from his father. His mother had to have at least one recessive allele, XHXh, and that's far more probable than XhXh because the hemophilia allele is not very common in the population. There's no way to tell if the father had the allele or not because the father gives the Y-chromosome to his sons and Y doesn't say anything about hemophilia.

Answer 2

In order for a female to be hemophiliac, she must have two "defective" Xs.
She took one X from each parent. So her father is hemophiliac for sure (since he has just one X) and her mother is either sick or has one defective X.
Male hemophiliac has only one X, which is expressed and so it must be defective. A male gets the X chromosome from his mother, so she has at least one defective X (can't tell about the other) and Y from father, so we can't tell anything about the father either.