Biology Hour____ Name______________________________
Instructor: Dr. Wexler
Assigned: 2/9/04
Due: 2/10/04

Sex-Linked Inheritance

Problem 1:
Hemophilia in humans is due to an
X-chromosome mutation. What will be the results of mating between a normal (non-carrier) female and a hemophilac male? Show your reasoning.

A.

half of daughters are normal and half of sons are hemophilic.

B.

all sons are normal and all daughters are carriers.

C.

half of sons are normal and half are hemophilic; all daughters are carriers.

D.

all daughters are normal and all sons are carriers.

E.

half of daughters are hemophilic and half of daughters are carriers; all sons are normal.




Problem 2:
A human female "carrier" who is heterozygous for the recessive, sex-linked trait causing red-green color blindness marries a normal male. What proportion of their male progeny will have red-green color blindness? Show your reasoning.

A. 100%

B. 75%

C. 50%

D. 25%

E. 0%







Problem 3:
Given: Women have sex chromosomes of
XX, and men have sex chromosomes of XY.

Which of a women's grandparents could not be the source of any of the genes on either of her X-chromosomes? Show your reasoning.

A. Mother's Father.

B. Father's Mother.

C. Mother's Mother.

D. Father's Father.

E. Mother's Mother and Mother's Father.









Problem 4:
A human female "carrier" who is heterozygous for the recessive, sex-linked trait red color blindness, marries a normal male.

What proportion of their female progeny will show the trait? Show your reasoning.

A. All

B. 1/2

C. 1/4

D. 0

E. 3/4