80. Which of the following BEST explains the "wobble" hypothesis proposed by Francis Crick?
(A) The genetic code is degenerate in that most amino acids have more than one codon.
(B) The genetic code is ambiguous in that each codon can specify more than one amino acid.
(C) The anticodon can pair with any part of the corresponding codon.
(D) The 5'-base of the anticodon can make non Watson-Crick hydrogen bonds with several different bases at the 3'-position of the codon.
(E) Inosine can pair up with C, G, or U.

76. Which of the following enzymes are aspartate protease ? ① Subtilisin； ② Cathepsin D； ③ HIV-protease； ④ Thrombin； ⑤ Pepsin (A) ①,②,③ (B) ①,②,④ (C) ①,②,⑤ (D) ②,③,④ (E) ②,③,⑤

77. Which of the following statements for the structure of proteins are CORRECT? ① A bond between amino acids is peptide bond. ② Disulfide bonds in proteins are formed by serine. ③ The amino acid sequence is the primary structure of proteins. ④ The coil-coiled motif is the tertiary structure of proteins. ⑤ The quaternary structure of proteins contains two or more polypeptide chains. (A) ①,③,⑤ (B) ②,③,④ (C) ②,③,⑤ (D) ①,③,④ (E) ①,②,③

78. In order to infect cells, the hemagglutinin of the influenza virus binds with ______ in the cell surface glycoproteins or glycolipids. (A) sialic acid (B) gluconic acid (C) N-acetylmuramic acid (D) uronic acid (E) muramic acid

79. In electron-transport chain, the transferring sequence of the electrons passing from NADH to oxygen is: (A) Complex I→Complex III→Complex IV→Complex V (B) Complex I→Complex II→Complex III→cytochrome c→Complex IV (C) Complex I→Q→Complex II→Complex III→cytochrome c→Complex IV (D) Complex I→Complex II →Complex III →Complex IV (E) Complex I→Q→Complex III→cytochrome c→Complex IV

81. Phospholipids show asymmetric distribution on membrane of erythrocytes. Which of the following phospholipids prefer to distribute on the outer leaflet of erythrocyte membrane? ① phosphatidylcholine； ② phosphatidylserine； ③ phosphatidylinositol； ④ sphingomyelin； ⑤ phosphatidylethanolamine (A) ①,② (B) ①,③ (C) ①,④ (D) ②,③ (E) ②,⑤

82. Mammalian phosphofructokinase, the major flux-controlling enzyme of glycolysis, is regulated by ① allosteric activator, fructose 2, 6-bisphosphate； ② allosteric inhibitor, ATP； ③ allosteric activator, AMP； ④ allosteric inhibitor, ADP； ⑤ allosteric activator, Citrate (A) ①,②,③ (B) ①,③,④ (C) ①,②,⑤ (D) ①,③,⑤ (E) ①,④,⑤

83. Misfolding of protein causes a broad range of disease. Which of the following human diseases linked to misfolding of proteins are CORRECT? ① Alzheimer’s disease, β-Amyloid peptide ； ② Creutzfeldt-Jakob disease, Prion protein ； ③ Cystic fibrosis, Superoxide dismutase I； ④ Hungtington’s disease, α-Synuclein； ⑤ Familial amyloidotic polyneuropathy, Transthyretin. (A) ①,②,③ (B) ①,②,④ (C) ②,③,⑤ (D) ③,④,⑤ (E) ①,②,⑤

84. Which of the following statements about the inhibition of enzyme activity is FALSE? (A) Transition state analogs can be used as competitive inhibitor. (B) Irreversible inhibition can be analyzed using Michaelis-Menten equation. (C) Increasing substrate concentration can counteract the effect of competitive inhibitor. (D) An uncompetitive inhibition does not affect the slope of the Lineweaver-Burk plot. (E) The irreversible inhibitor is covalently linked with the catalytic residue at the active site of the enzyme.

85. Which of the following enzymes are involved in the purine salvage pathways? ① GMP synthetase； ② Adenine phosphoribosyl transferase； ③ Purine nucleoside phosphorylase； ④ Hypoxanthine-guanine phosphoribosyltransferase； ⑤ Adenylosuccinate lyase (A) ①,② (B) ②,③ (C) ③,④,⑤ (D) ②,④ (E) ②,③,④

86. Which of the following statements for cholesterol are CORRECT? ① Cholesterol is a precursor of lanosterol. ② Cholesterol is a component of cell membrane in human erythrocyte. ③ Cholesterol is a precursor of bile acids. ④ Cholesterol is terpene-based lipid. ⑤ Cholesterol reduces the transition temperature of phospholipids in cell membrane. (A) ①,②,③ (B) ①,③,⑤ (C) ①,②,④ (D) ②,③,④ (E) ②,④,⑤