Question

Two forms of hemophilia are determined by genes on the X chromosome in humans. Assume that a phenotypically normal woman whose father had hemophilia is married to a normal man. What is the probability that their first son have hemophilia?

a) 1/3
b) 0
c) 1/4
d) ½
e) 100%

Answer 1

The probability that the first son of a phenotypically normal woman and normal man will have hemophilia is 1/2.

Step-by-step explanation:

In a mating between a phenotypically normal woman whose father had hemophilia and a normal man, the probability that their first son will have hemophilia is 1/2 (d). Hemophilia is determined by genes on the X chromosome, so the son has a 50% chance of inheriting the hemophilia gene from the mother and being affected by the disorder. Daughters do not inherit the disorder but have a 50% chance of being carriers.