17. All are true for DNA polymerase   except  :
(A) generates dsDNA from ssDNA.
(B) synthesizes new strands by adding successive nucleotides in the 5'→3' direction.
(C) copies the sequence of nucleotides of one strand in a complementary fashion.
(D) requires a primer with a free 5'-OH end, but the 3'-end may be phosphorylated.
(E) copies the sequence of nucleotides of one strand to form a new second strand.

13. Which one is incorrect regarding β and ω oxidation of fatty acids? (A) β oxidation takes place in mitochondrial inner matrix. (B) ω oxidation occurs in ER. (C) Mono-unsaturated FA needs enoyl-CoA isomerase. (D) Final products contain acetyl-CoA. (E) The length of fatty acid ＞ 12C utilizes ω oxidation.

14. Which one is not the fate of cholesterol? (A) Incorporated into the plasma membranes in hepatocytes. (B) Synthesis of biliary cholesterol and bile acid. (C) Synthesis of vitamin D. (D) Formation of triacylglycerol in VLDL. (E) Synthesis of hormones for extrahepatic tissues.

15. Which lipoprotein contains the most abundant cholesterol? (A) Chylomicron. (B) VLDL. (C) LDL. (D) IDL. (E) HDL.

16. Which one has a less relevance to cardiovascular diseases? (A) High LDL. (B) High HDL. (C) Trans unsaturated fatty acid. (D) Long Saturated fatty acid. (E) 06 fatty acid.

18. The higher the ____ content of a DNA, the ____ the melting temperature, and the ____ the ionic strength, the ____ the melting temperature. (A) G:C； higher； lower； lower (B) G:C； lower； higher； lower (C) G:C； higher； higher； lower (D) A:T； higher； higher； lower (E) A:T； lower； lower； higher

19. RNA is ____ stable to alkaline hydrolysis than DNA because RNA's vicinal ____ group makes the 3'-phosphodiester bond susceptible to ________ cleavage. (A) more； 2'-OH； nucleophilic (B) more； 2'-OH； electrophilic (C) less； 2'-OH； nucleophilic (D) less； 3'-OH； nucleophilic (E) more； 3'-OH； electrophilic

20. The function of DNA topoisomerases is: (A) packaging DNA into nucleosomes. (B) forming cruciform DNA. (C) unwinding G:C rich areas in DNA. (D) breaking one or more strands of DNA, winding them tighter or looser, and rejoining the ends. (E) promoting DNA hybridization.

21. Alanine is formed from transamination of: (A) asparagine. (B) aspartame. (C) oxaloacetate. (D) citrate. (E) pyruvate.

22. Which statement about ribonucleotide reductase is not true: (A) It is an enzyme that catalyzes the formation of dADP, dGDP, dCDP and dTDP. (B) The reaction catalyzed by ribonucleotide reductase is strictly conserved in all living organisms. (C) The immediate reducing power of ribonucleotide reductase is provided by thioredoxin. (D) Consists of two non-identical subunits. (E) Free radical is involved in the catalysis.

23. Which statement about thymidine kinase (TK) is not true: (A) Thymidine kinase catalyzes the reaction: deoxythymidine + ATP → TMP + ADP. (B) Thymidine kinases have a key function in the synthesis of RNA. (C) Mammals have two isoenzymes, TK1 and TK2. (D) Certain viruses also carry gene for the expression of viral thymidine kinases. (E) None of the above.