83. Lesch-Nyhan Syndrome is due to a deficient in ________ activity.
(A) Adenosine deaminase
(B) Adenine phosphoribosyltransferase
(C) Guanine deaminase
(D) Hypoxathine-guanine phosphoribosyltransferase
(E) AMP deaminase

79. The reverse transcriptases possess the function of ① RNA-directed DNA polymerase activity ② Primase ③ DNA-directed DNA polymerase activity ④ RNase H activity ⑤ Helicase (A) ①②③ (B) ①②④ (C) ①②⑤ (D) ①③④ (E) ①③⑤

複選題80. Which of the following statements about the catabolism of free pyrimidines in the human body is CORRECT? ① Free cytosine and uracil are not salvaged ② Degradation of free cytosine produces β-alanine, CO2, and ③ Degradation of free uridine produces β-aminoisobutyric acid, CO2, and ④ Free thymine are recycled for synthesizing nucleosides (AB) ①②③ (AC) ①②④ (AD) ①② (AE) ①③ (BC) ①③④ (BD)一律送分

81. Which of the following statements about allosteric regulation is TRUE? (A) An allosteric inhibitor of an enzyme can be a competitive inhibitor. (B) An allosteric activator of an enzyme may reduce the apparent Vmax. (C) An allosteric activator cannot be substrate of allosteric enzymes. (D) An allosteric activator reduces the apparent Km. (E) An allosteric effector is a transition state analogue.

82. Which of the following products are produced by the β-oxidation of fatty acid? ① FADH2 ② NAD+ ③ NADH ④ NADPH ⑤Acetyl-CoA (A) ①②⑤ (B) ①③⑤ (C) ①④⑤ (D) ②③⑤ (E) ②④⑤

84. Eukaryotic mRNAs may be modified after synthesis via the following reactions except: (A) Remove noncoding regions (introns) and joining the coding regions (exon) by spliceosome (B) Self-splicing of mitochondrial or chloroplast mRNA (C) Cleavage at the 3’ end of the primary transcript (D) Addition of a string A residues at the 3’ end (E) Addition of a methyl-cytosine residue at the 5’ end

85. An enzyme is found that catalyzes the reaction S → P. Researchers find that the Km for the substrate S is 4 μM, and the . In an experiment, [S]=6 mM, and . What was the enzyme concentration used in the experiment? (A) 24 nM (B) 24 μM (C) 120 nM (D) 120 μM (E) 80 nM

86. Which pair of enzymes is involved in glycolysis but NOT in gluconeogenesis? (A) Hexokinase and phosphohexose isomerase (B) Phosphofructokinase and pyruvate kinase (C) Phosphofructokinase and phosphoglycerate kinase (D) Phosphoglycerate kinase and pyruvate kinase (E) Phosphoglycerate mutase and enolase

87. Amino acids can be classified into different groups based on the R-group structure. Which class of amino acids contains only nonessential amino acids? (A) Hydrophobic (B) Aromatic (C) Polar, uncharged (D) Positively charged (E) Negatively charged

88. The functions of cholesterol include all the following except: (A) A precursor of bile (B) A precursor of vitamin D (C) As an intracellular energy source (D) Sustain cell membrane structure (E) Essential for producing steroid hormone

89. The following statements about lipid transport are all correct except: (A) Dietary triacylglycerols and cholesterol from intestine is carried by chylomicrons to muscle and adipose tissues. (B) VLDL carries triacylglycerols and cholesterol from liver to muscle and adipose tissues. (C) LDL carries mainly triacylglycerol from liver to muscle and adipose tissues. (D) HDL synthesized from liver picks up cholesterol in the bloodstream and transported back to liver. (E) The loss of triacylglycerols converts VLDL to LDL.