Why were both women in the family tree above free of the disease?
(A) They were lucky because they didn’t receive an X chromosome with the diseased allele.
(B) They cannot get hemophilia because it is associated only with a diseased Y chromosome.
(C) They are carriers and will get the disease only if they have children.
(D) They have at least one normal (unaffected) copy of the X chromosome.

Hemophilia is an X-linked disease associated with the inability to produce specific proteins in the blood-clotting pathway. In Figure 1, the family members afflicted with the disease are shown with filled-in squares (male) or circles (females). A couple is trying to determine the likelihood of passing on the disease to their future children (represented by the ? symbol above) because the hemophilia runs in the woman’s family.

Transcribed Image Text:

O Male Female O ㅂㅇㅁ ?