17. Which of the following is not a reducing sugar?
(A) glyceraldehyde
(B) trehalose
(C) cellobiose
(D) maltose
(E) fructose

13. Metal ion catalysis is facilitated by any of several mechanisms, including (A)electrophilic activity, which stabilizes negative charges on an intermediate. (B) promoting formation of nucleophiles by affecting adjacent molecules. (C) direct binding to substrate, increasing substrate-enzyme contacts. (D) A and C. (E) all of the above.

14. Restriction endonucleases cut DNA at specific sites. How many different patterns can be formed by a four-base sequence combination of any four bases? (A) 64 (B) 256 (C) 16 (D) 1024 (E) 4096

15. Hemoglobin-binding of oxygen is best described as a (A) concerted model. (B) Michaelis-Menten model. (C) sequential model. (D) combination of sequential and concerted models. (E) None of the above.

16. Which of the following is an epimer pair? (A)D-glucose and L-glucose (B) D-glucose and D-galactose (C) a-D-glucose and ẞ-D-glucose (D) D-glucose and D-fructose (E) D-mannose and D-galactose

18. Which of the following is not a heteropolysaccharide? (A)agarose (B) chitin (C) peptidoglycan (D) heparin (E) all of the above

19. Which of the following molecules or substances contain, or are derived from, fatty acids? (A)sphingolipids (B) prostaglandins (C) beeswax (D) all of the above (E) none of the above

20. The fluidity of the lipid side chains in the interior of a bilayer is generally increased by: (A)an increase in temperature. (B) an increase in fatty acyl chain length. (C) a decrease in the number of double bonds in fatty acids. (D) an increase in the percentage of phosphatidyl ethanolamine. (E) all of the above.

21. Which of these statements is generally true of integral membrane proteins? (A)Their hydropathy plots reveal one or more regions with a high hydropathy index. (B) They are glycosylated. (C) They are more stable than cytosolic proteins. (D) They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer. (E) None of the above.

22. Which of the following molecules cannot serve as the starting material for the synthesis of glucose via gluconeogenesis in mammals? (A)glycerol (B) lactate (C) glycine (D) oxaloacetate (E) acetate

23. Entry of acetyl-CoA into the citric acid cycle is decreased when: (A)the ratio of /[NADH] is high. (B) NADH is rapidly oxidized through the respiratory chain. (C) the ratio of [ATP]/[ADP] is low (D) the ratio of [ATP]/[ADP] is high. (E) [AMP] is high.