Question

11. A boy, whose parents and grandparents had normal vision, is color-blind. What are the

genotypes for his mother and his maternal grandparents? Use XB for the dominant

normal condition and Xb for the recessive, color-blind phenotype

12. In humans, sickle cell anemia is a disease caused by a mutation of a single locus gene

which codes for an important blood protein. The allele for the normal protein (S) is

dominant to that for the one causing sickle cell anemia. What gametes would be

produced by individuals resulting from a SS x ss cross?

13. A man with group A blood marries a woman with group B blood.

a. What are the genotypes of these individuals?

b. What blood groups and frequencies would you expect in offspring from this

marriage?

14. Phenylketonuria (PKU) is an inherited disease caused by a recessive allele. If a woman

and her husband are both carriers, what is the probability of each of the following?

a. all three of their children will be of normal phenotype

b. one or more of the three children will have the disease

c. all three children will have the disease

d. at least one child out of three will be phenotypically normal

(Note: Remember that the probabilities of all possible outcomes always add up to 1)

Answer 1