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

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

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

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.

90. Which of the following posttranslational modifications is applied to produce active insulinmolecules in pancreatic β cells:① Phosphorylation of Ser residues② Glycosylation of Asn residues③ Cleavage of a signal sequence④ Proteolytic cleavage of internal sequences⑤ Formation of disulfide bonds(A) ③④⑤ (B) ②③④ (C) ②⑤ (D) ①②④⑤ (E) ①②③⑤

1.An object starts from rest at the origin and moves along the x axis with a constant acceleration of 4 m/s2. Its average velocity as it goes from x = 2 m to x = 8 m is: (A) 1 m/s (B)2m/s(C)3m/s (D) 5m/s (E) 6 m/s

2.A ball is thrown horizontally from the top of a 20-m high hill. It strikes the ground at an angle of ㆍ450. With what speed was it thrown? Use g = 10 m/s2.  (A) 14m/s (B) 20m/s (C) 28 m/s (D) 32 m/s(E) 40 m/s

3.The speed of a particle moving in a circle 2.0 m in radius increases at the constant rate of 6.0 m/s. At an instant when the magnitude of the total acceleration is 10.0 m/s, what is the speed of the particle?(A)3.0 m/s(B)4.0 m/s (C) 5.0 ml/s (D)6.0 m/s(E)8.0 m/s