Question

Hemophilia is a recessive sex linked trait. A male hemophiliac and a phenotypically normal female have a girl that is hemophiliac. Which of the following statements is correct? A. The daugjter inherited a dominant allele from her mother. B. The mother is a carrier of hemophilia. C. The genotype of the mother is X^h X^h. D. The genotype of the father is X^H Y.

Answer 1

Answer:

B

Explanation:

I went ahead and drew a quick pedigree. Circles being female, square male; darkened means they have the disease.

• It cannot be A because the daughter has no dominant alleles.

• It cannot be C because the mother does not have the illness, and she had to have been able to pass a recessive allele to the daughter. So the mother has to be (X^H/X^h)
• It cannot be D because if D were true then the father would not have hemophilia. Since the father has only one x chromosome he needs just one recessive allele to have the disease.

So the answer is B because while the mother is not X^h/X^h she still carries one recessive allele for hemophilia and one dominant for normal.

Answer 2

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its A

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