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

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

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.

24. Which enzyme is the major regulatory control point for β-oxidation? (A)pyruvate carboxylase (B) acetyl CoA dehydrogenase (C) methylmalonyl CoA mutase (D) enoyl CoA isomerase (E) carnitine acyl transferase I