10. Cholesterol is the most common steroid in animals and precursor for all other steroids in animals. The number of the carbon labeled "* "in the cholesterol showed below is

(A) 15
(B) 18
(C) 20
(D) 19
(E) 21.

6. The amino acid with a side-chain pKa near neutrality and which therefore plays an important role as proton donor and acceptor in many enzyme catalyzed reactions is: (A) Met (B) Cys (C) Pro (D) Ser (E) His.

7. What is the overall net charge on the peptide D-F-A-R-I-G at pH 7.0? (A) +2 (B) +1 (C) 0 (D) -1 (E) -2.

8. If a restriction site of 6 bases starts with 5'-TGC, what are the last three bases in the sequence? (A) 5'-CGT-3' (B) 5'-GCA-3' (C) 5'-ACG-3' (D) 5'-CGG-3' (E) none of the above.

9. Ribosomes are about ______ RNA and ______ protein. (A) 2/3； 1/3 (B) 1/3； 2/3 (C) 3/4； 1/4 (D) 1/4； 3/4

11. Which one is a nonreducing sugar? (A) Lactose (B) Maltose (C) Cellobiose (D) Sucrose (E) Isomaltose.

12. What is the name of this molecule? (A) α-D-ribopyranose (B) α-L-ribopyranose (C) β-D-ribopyranose (D) β-L-ribopyranose (E) none of above. 

13. Which one is the cleavage site of Phospholipases D?

14. In a sample of double-stranded DNA containing 32% cytosine, the percentage of adenine would be (A) 32% (B) 18% (C) 68% (D) 36% (E) Insufficient information to answer question.

15. Which of the following supposedly has the greatest affinity to the proline racemase? (that catalyzes the following reaction) A transition state analog:(A) L-Proline (B) D-Proline (C) The planar transition state (D) Pyrrole-2-carboxylate (E) Proton.

16. A plot of 1/v vs. 1/[S] for an enzyme catalyzed reaction gave a line with an equation of 1/v = 0.4/[S] + 0.2. The same enzyme with an inhibitor present gave a line with an equation of 1/v = 0.4/[S] + 0.8. Which of the following statements is true? (A) the type of inhibition is competitive (B) the type of inhibition is noncompetitive (C) the type of inhibition is uncompetitive (D) the Km with the inhibitor present has decreased (E) None of the above.