21. Which type of damage to DNA structure is most likely to be caused by UV light?
(A) Deamination
(B) Pyrimidine dimers
(C) Depurination
(D) Depyrimidination
(E) Hydrolysis of the phosphodiester bond

17. In the active site of chymotrypsin, which of the following is the amino acid residue arrangement order of the catalytic triad? (A) Asn…Lys…His (B) Asp…His…Ser (C) His…Asp…Tyr (D) Asn…Ser…Cys (E) His…Cys…Asp

18. Which of the following is a DNA sequence? (A) Coactivator (B) Corepressor (C) Enhancer (D) Inducer (E) Transactivator

19. Poly-lysine exhibits a random coil structure at neutral pH. What kind of interaction can cause its formation of a random coil structure? (A) Covalent bond (B) Hydrogen bond (C) van der Waals interaction (D) Electrostatic interaction (E) Hydrophobic interaction

20. Which one can not bind to the origin of replication of E. coli (oriC)? (A) DnaA (B) DnaB (C) Integration host factor (IHF) (D) Histone-like protein (HU) (E) Tus

22. Which compound is an intermediate of the β-oxidation of fatty acids? (A) CH3—(CH2)20—CO—COOH (B) CH3—CH2—CO—CH2—CO— OPO32– (C) CH3—CH2—CO—CH2—OH (D) CH3—CH2—CO—CO—S—CoA (E) CH3—CO—CH—CO—S—CoA

23. Which of the following enzymes requires coenzyme B1 as cofactor? (A) Pyruvate decarboxylase (B) Malic enzyme (C) Alcohol dehydrogenase (D) Citrate synthase (E) Pyruvate carboxylase

24. Which of the following statements is not correct? (A) Bacterial peptidoglycan contains (β1→4) glycosidic linkage. (B) Cellulose contains (β1→4) glycosidic linkage. (C) Starch contains (α1→6) glycosidic linkage. (D) Glycogen contains (α1→4) glycosidic linkage. (E) Lactose contains (α1→4) glycosidic linkage.

25. For each molecule of acetyl-CoA that enters the citric acid cycle, which of the following sets represents the net products of the cycle? (A) 2 CO2, 2 NADH, 2 FADH2, 1 GTP, 1 oxaloacetate (B) 2 CO2, 3 NADH, 1 FADH2, 2 GTP, 1 oxaloacetate (C) 2 CO2, 2 NADH, 1 FADH2, 2 GTP, 0 oxaloacetate (D) 2 CO2, 3 NADH, 1 FADH2, 1 GTP, 1 oxaloacetate (E) 2 CO2, 3 NADH, 1 FADH2, 1 GTP, 0 oxaloacetate

26. Fatty acids are activated to acyl-CoA, however, why the acyl group is further transferred to carnitine for β-oxidation? (A) Carnitine is required to oxidize NAD+ to NADH. (B) Acyl- CoAs easily cross the mitochondrial membrane, but the fatty acids themselves will not. (C) Acyl-carnitines readily cross the mitochondrial inner membrane, but acyl-CoAs do not. (D) Fatty acids cannot be oxidized by FAD unless they are in the acyl-carnitine form. (E) Carnitine can be oxidized to provide additional energy in mitochondria.

27. Which of the following is the building block for the biosynthesis of phenylalanine, tyrosine, and tryptophan? (A) Pyruvate (B) Phosphoenolpyruvate (C) Acetyl-CoA (D) α-Ketoglutarate (E) Ribose-5-phosphate