C 5. Compared to X-linked dominant diseases, what is the prevalence of X-linked recessive diseases?
a. Less common
b. Equally common
c. More common
d. Cannot be determined
Q8. Why are women somewhat protected from X-linked disorders?
a. They have two X chromosomes
c. They have more autosomes
b. They have one X and one Y chromosome
d. They lack the gene for X-linked disorders
How many mutant X chromosomes are needed for a female to express X-linked recessive diseases?
a. None
c. Two
b. One
d. Three
C 7. What term is used to describe females who carry the gene for a disorder but do not express the disorder themselves?
a. Expressors
c. Carriers
b. Dominants
d. Affected
a 8. What is the inheritance pattern in X-linked recessive diseases for sons of an affected mother?
a. All sons are affected
b. None of the sons are affected
c. Only the first-born son is affected
d. Sons have a 50% chance of being affected
II. PROBLEM SOLVING. Solve the following multiple alleles and sex-linked trait problems. Set up Punnet squares for each of the crosses given below on a separate sheet of paper.
MULTIPLE ALLELES:
9-13: It was suspected that two babies had been exchanged in a hospital. Mr. and Mrs. Jones received baby #land Mr. and Mrs. Simon received baby #2. Blood typing tests on the parents and the babies showed the following:
Mr. Jones: Type A
Mrs. Jones: Type O
Baby #1: Type A
Baby #2: Type B
Q9. What is the blood type of Mr. Simon?
a. Cannot be determined
b. Type A
c. Type O
d. Type B
Q10. What is the blood type of Mrs. Simon?
a. Cannot be determined
b. Type A
c. Type O
d. Type B
Q11. Whose baby was mistakenly given to Mr. and Mrs. Jones?
a. Baby #1
b. Baby #2
c. Cannot be determined
d. None of the above
Q12. What blood type(s) could the biological parents of baby #1 have?
a. Type A only
b. Type AB only
c. Type A or Type AB
d. Cannot be determined
Q13. What blood type(s) could the biological parents of baby #2 have?
a. Type B only
b. Type AB only
c. Type B or Type AB
d. Cannot be determined
SEX-LINKED TRAITS:
14-16: In fruit flies, gray eye color (G) is dominant over red eye color (g). A gray-eyed female fly is crossed with a red-eyed male fly. The resulting offspring are as follows:
Gray-eyed females: 106
Gray-eyed males: 79
Red-eyed females: 90
Red-eyed males: 106
Q14. What is the genotype of the gray-eyed female fly?
a. GG
b. Gg
c. gg
d. Cannot be determined
Q15. What is the genotype of the red-eyed male fly?
a. GG
b. Gg
c. gg
d. Cannot be determined
Q16. What is the mode of inheritance for eye color in fruit flies?
a. Autosomal dominant
b. Autosomal recessive
c. X-linked dominant
d. X-linked recessive