Hemophiliacs have blood that does not coagulate well, and they often die at a young age. The disease allele is recessive and X-linked. Which of the following is the BEST prediction about the offspring of a hemophiliac male and a nonhemophiliac female who is a carrier for the disease?
A) All children would be hemophiliac.
B) All females would be hemophiliac.
C) All males would be hemophiliac.
D) Some males and females could be hemophiliac.

Question

Quizplus · Accepted Answer

The hemophiliac male would only pass his disease allele onto his daughters (who would then be carriers) and not to his sons. The nonhemophiliac female who is a carrier would have a 50% chance of passing on the disease allele to each of her offspring. Therefore, some of their sons would be hemophiliac (since they would inherit the X chromosome with the disease allele from their carrier mother) and some would not (since they would inherit the Y chromosome from their father instead). Their daughters would have a 50% chance of being carriers (since they would inherit one X chromosome with the disease allele from their mother and one normal X chromosome from their father) and a 50% chance of not being carriers (since they could inherit the normal X chromosome from their mother instead).

Hemophiliacs Have Blood That Does Not Coagulate Well, and They