13. Which of the following amino acid(s) appear to be coded by triplets containing 2 A's and 1 C?
(A) Asparagine
(B) Glutamine
(C) Proline
(D) Threonine
(E) Lysine 

9. The reason it takes approximately one hour before the first radioactively labeled mitotic cells are observed is that (A) cells must repair thymidine-induced DNA damage before entering G2 (B) the cells get out of synchrony as they proceed through the cell cycle (C) the period of thymidine labeling is 5 minutes (D) G2 lasts 1 hr (E) M phase lasts 1 hr

10. What percent of labeled cells are in M phase at 4 hours after exposure to labeled thymidine? (A) 100 (B) 33 (C) 20 (D) 6 (E) 0

11. If the length of G2 were increased by one hour, which of the following statements would be true regarding the slope of the line from the point of the first appearance of labeled mitotic cells to the first point at which all the mitotic cells were labeled? (A) It would stay the same. (B) It would decrease. (C) It would increase. (D) It would switch from a positive to a negative slope. (E) No conclusion regarding the slope of the line can be drawn.

12. The expected frequency of the triple CCC in the A: C=1:5 copolymer should be (A) 1/8 (B) 5/6 (C) 7/8 (D) 15/216 (E) 125/216

14. Which mutant would have a mutation in the "strong" promoter? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

15. Which mutant(s) would have a mutation in the repressor? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

16. Which mutant(s) would have a mutation in the operator? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

17. Which mutant(s) would have a mutation in the protein coding region? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5 

18. Which element(s) are cis-acting? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5

19. Which element(s) are trans-acting? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5