110年 - 110 國立中山大學碩士暨碩士專班招生考試_生科系碩士班/乙組:生物化學#105553

1. What makes carbon such an abundant element in biomolecules? (A)It can form up to five bonds by sharing its electrons. (B) It forms only single bonds. (C)It provides low bond energy. (D)It forms stable covalent bonds by electron pair sharing. (E)It does not usually bond to other carbons, allowing a more diverse combination of elements.

2. Arrays of filaments in eukaryotic cells that give the cell its shape and its capacity to move are called the: (A)plasma membrane. (B) smooth endoplasmic reticulum. (C) cytoskeleton(D) lysosome.(E)Golgi body.

3. All of the following functions of an enzyme are true EXCEPT:(A) Enzymes help to catalyze virtually every metabolic reaction.(B) Enzymes mediate the rates of cellular reaction in proportion to cellular requirements.(C) Enzymes are sensitive to temperature, pH, and concentration changes.(D) An increased activity of an enzyme increases the amount of energy produced.(E) Enzymes are used as a catalyst to increase reaction rates many orders of magnitude.

4. Buffers have all of the following characteristics EXCEPT: (A) They have relatively flat titration curves at the pH(s) where they buffer. (B) They resist changes in their pH as acid or base is added. (C)They are typically composed of a weak acid and its conjugate base. (D) They buffer best for polyprotic acids half-way between the two pKa values. (E)Buffer where the amounts of conjugate base are nearly equivalent to the amounts of weak acid.

5. The hydrolysis of a phosphate from which of the following molecules is most thermodynamically favorable?(A) ADP (B) glucose phosphate (C)adenosine-5'-diphosphate (D)phosphoenolpyruvate (E)adenosine-5'-triphosphate

6. To predict whether pairs of coupled reactions will proceed spontancously: (A)Subtract the smaller from the larger △G. (B) Sum the for each reaction. (C)Add the △S values for each reaction at constant temperature. (D)The absolute value of the positive must be larger than the value of the negative .(E)None are true.

7. The difference between serine and homoserine is the same as between cysteine and homocysteine. This change from the common amino acid is: (A)one additional -CH₂- group.(B) one additional -COOH group. (C)two additional -NH₂ groups.(D) presence of a ring system. (E)one additional -NH₂ group.

8. All of the amino acids EXCEPT________have both free o-amino and free a-carboxyl groups.(A)aspartic acid(B)proline(C)asparagine(D)lysine(E)valine

9. The amino acid with a side-chain pKa near neutrality and which therefore plays an important role as proton donor and acceptor in many enzyme catalyzed reactions is:(A)histidine.(B)cysteine.(C)proline.(D)serine.(E)methionine.

10. Ninhydrin has all these properties EXCEPT: (A)It reacts with an amino acid by oxidatively deaminating its amino group. (B) It can be used to detect the location of amino acids following chromatography. (C)It produces a purple colored product upon reaction with alanine.(D) It produces a yellow product upon reaction with histidine. (E)It can be used to quantify most amino acids.

11. Proteins with two different polypeptide chains are:(A) monomeric proteins. (B) trimeric proteins. (C)homodimeric proteins. (D)heterodimeric proteins. none of the above.

12. Fibrous proteins, such as collagen, have which one of the following properties? (A)Highly soluble in water. (B) Their hydrophilic residues are directed into the interior of the protein. (C)Exhibit enzymatic activity. (D)Serve structural roles in the cell.(E) Monomeric.

13. Molecules of a given protein have all EXCEPT: (A) fixed amino acid composition. (B) a defined amino acid sequence.(C) a sequence read from C-terminal end to N-terminal end.(D) an invariant molecular weight.(E) a nucleotide sequence from which they are encoded.

14. A protein's particular conformations are all EXCEPT: (A)The overall three-dimentional architecture of the protein. (B) Achieved by breaking and reforming covalent bonds. (C)Achieved by rotations about each single bond along the peptide backbone. (D)The result of amino acid side-chain interactions. (E)None, all are true.

15. Why should the core of most globular and membrane proteins consist almost entirely of a-helix and β-sheets?(A)Hydrogen bonded structures must be kept away from water solvent.(B) Highly polar N-H and C-O moieties of the peptide backbone must be neutralized in the hydrophobic core of the protein. (C)Hydrogen bonding only occurs in the core of proteins. (D)Trapped water stabilizes the helix and sheet structures.(E) None are true.

16. All are structural and functional advantages to quaternary structure EXCEPT: (A)cooperativity. (B) stability. (C)bringing catalytic sites together.(D) genetic economy and efficiency.(E) all are true.

17. How do catalysts work to accelerate a chemical reaction?(A) They raise the average energy of the reactants. (B) They provide a means of acceleration by being completely consumed in the reaction. (C)They lower the energy of activation.(D) They lower the overall free energy change of the reaction. (E)They raise the overall free energy change of the reaction.

18. All are true for kcat EXCEPT :(A) referred to as the molecular activity of the enzyme. (B) called the turnover number of the enzyme. (C) measures the maximal catalytic activity or kinetic efficiency of an enzyme.(D) defines the number of substrate molecules converted into product/enzyme molecule/unit of time when the enzyme is saturated with substrate. (E)all are true.

19. The enzyme-catal yzed reaction rate will be increased if the energy level of ES can be increased by all EXCEPT:(A) destabilization of ES by strain. (B) loss of entropy due to binding of E and S. (C)destabilization of ES by distortion. (D)destabilization of ES by solvation. (E)destabilization of ES by electrostatic effects.

20. The good transition state analog is one which would serve also as an effective:(A)competitive inhibitor.(B)noncompetitive inhibitor.(C)allosteric inhibitor.(D)mixed-noncompetitive inhibitor.(E)irreversible inhibitor.

21. All are true for low-barrier hydrogen bonds EXCEPT:(A)The hydrogen is centered between the two heteroatoms.(B)The interactions are more covalent.(C)The bond order approaches 0.5 for both O-H interactions.(D)The barrier that the hydrogen atom must surmount to exchange oxygens becomes lower.(E)All are true.

22. The mechanism of chymotrypsin involves which of the following elements? (A)deprotonation of an active site Asp residue by His to start the reaction (B) formation of an acyl-enzyme intermediate that must be hydrolyzed to complete the reaction (C)stabilization of the positively charged His by a GIn residue (D)direct deprotonation of water by His to generate a hydroxide ion for initiation of the reaction (E)both a and b occur

23. Which statement below about contrasting Hb and Mb is FALSE?(A)Hb shows sigmoidal, whereas Mb shows hyperbolic oxygen saturation curves.(B) Hb shows cooperativity, whereas Mb does not.(C)Hb binds O₂ more tightly than Mb.(D)Oxygen binds to a ferrous ion in both proteins.(E)Hb-oxygen binding is dependent on physiological changes in pH, whereas Mb-oxygen binding is not.

24. Carbon dioxide affects O₂binding to Hb by:(A)Hb competing with carbonic anhydride for CO₂.(B)directly binding to heme-Fe in the oxygen binding site.(C)forming iron carbonate with the heme-iron.(D)forming' where the H+ is an antagonist to oxygen binding to Hb.(E)formingthat combines with H* to increase CO₂ binding.

25. The enantiomer of D-mannose would be: (A)D-galactose. (B) L-glucose. (C)D-glucose. (D)L-mannose.(E) L-arabinose.

26. Cellulose is a: (A)(1→4)-a-D-mannopyranan. (B)(1→4)-β-D-glucopyranan. (C)(1→6)-a-D-glucopyranan. (D)(1→4)-β-D-galactopyranan. (E)(1→6)- a-D-mannopyranan.

27. Which of the following lipids is correctly defined? (A)triacylglycerol: formed from glycerol and 3 fatty acids, primary lipid of membranes (B) phospholipid: contains glycerol with 2 fatty acids and a phosphate, very often forms bilayers (C)wax: contains a fatty acid and alcohol, used primarily for energy storage (D)cholesterol: the primary component of "saturated" fats palmitic acid: the most commonly produced unsaturated fatty acid in animals

28. Membranes with unsaturated fatty acids in their components are more flexible and fluid because: (A)Unsaturated fatty acids pack closely together to form ordered arrays. (B)Unsaturated fatty acids bend at the double bond preventing close packing.(C) Saturated fatty acids have a "kink" that produces more fluid aggregates. (D)Unsaturated fatty acids have cis double bonds that prevent formation of the "kink.(E) All of the above are correct.

29. Hydropathy plots for transport proteins are utilized to reveal: (A)Amino acid residues which may be highly modified. (B) Amino acid residues which may be directly involved in facilitated transport. (C)Stretches of amino acid residues that make up hydrophobic regions, which may be directly associated with the lipid bilayer. (D)Amino acid residues which are hyper-reactive due to their location. e.Whether there is interaction between N-terminal and C-terminal amino acids.

30. Which of the following is the major advantage of a multi-enzyme complex? (A)It's large size enables it to span an entire membrane (B) The product of one enzyme is passed directly to the next enzyme without the possibility of diffusion (C)Multi-enzyme complexes are much less likely to be inhibited (D)all of the above none of the above

31. The enzymes of glycolysis and those of the citric acid cycle are found in which cellular compartments in muscle cells? (A)both in the cytoplasm (B) glycolysis in cytoplasm and citric acid cycle in mitochondria (C) both in mitochondria (D)glycolysis in cytoplasm and citric acid cycle in lumen of the endoplasmic reticulum (E)both in the lumen of the endoplasmic reticulum

32. Which of the following has the most highly exergonic hydrolysis (considering that only the highest energy bond is hydrolyzed)? (A)phosphoenolpyruvate (B) fructose-6-phosphate(C) 1,3-bisphoshpoglycerate (D)2,3-bisphoshpoglycerate (E)fructose-1,6-bisphosphate

33. The oxidation of one mole of glucose by anaerobic glycolysis yields a net of: (A) two moles of lactate and two moles of ATP. (B) two moles of lactate, two moles of NADH, and two moles of ATP. (C)two moles of lactate and six moles of ATP. (D)two moles of pyruvate and two moles of ATP. (E)two moles of pyruvate, two moles of NADH, and four moles of ATP.

34. The following statements are correct about the reaction catalyzed by the pyruvate dehydrogenase complex EXCEPT:(A) It is the link between glycolysis and the TCA cycle (B) The activity of the complex is regulated by the phosphorylation of EppH. (C)NAD⁺ is the direct oxidant of reduced lipoamide. (D)An FAD is covalently linked to the EpLD, the lipoamide dehydrogenase component.(E) Although EppH is called "pyruvate dehydrogenase" it is not a dehydrogenase.

35. Which enzymes of the TCA cycle catalyze oxidative decarboxylation reactions? (A)malate dehydrogenase and citrate synthase (B) fumarase and succinate debydrogenase (C)a-ketoglutarate dehydrogenase and succinate dehydrogenase (D) isocitrate dehydrogenase and o-ketoglutarate dehydrogenase (E)aconitase and succinate dehydrogenase

36. Does electron transport stop if rotenone is added? Why? (A)Yes, there is not an electron source. (B) No, rotenone is not strong enough to inhibit all of the electron transport chain. (C)No, there is still a source of electrons from Complex II. (D)Yes, totenone inhibits complex III, therefore, electrons can not be passed on. Can not be determined from the information given.

37. Which complex will be affected if rotenone is added?(A)complex I(B)complex II(C)complex III(D)complex IV(E)none, it is an uncoupler

38. Chloroplasts consist of a folded inner membrane called the____________，which is organized into paired folds called___________.(A)thylakoid membrane; stroma(B)lamellae; thylakoid membrane(C)thylakoid membrane; lamellae(D)stroma; thylakoid membrane(E)lamellae; stroma

39. Carotenoids have primary roles in photosynthesis as: (A)accessory light-harvesting and photooxidation. (B) accessory light-harvesting and photoprotection from reactive oxygen species. (C)resonance transfer pigments and photooxidation. (D)resonance transfer and photodiffusion protection. none are true.

40. Many chlorophyll molecules absorb light and direct the energy to the reactive centers. The transfer of this absorbed energy is called:(A) fluorescence transfer. (B) redox transfer.(C) resonance energy transfer. (D)photochemical emission.(E) energy transduction.

41. The endoplasmic reticulum bound enzyme that hydrolyzes glucose-6-phosphate to glucose in liver is: (A)glucokinase. (B) glucose oxidase.(C)hexokinase. (D). phosphoglucomutase. (E)glucose-6-phosphatase.

42. The energy input for the synthesis of glycogen occurs during which of the following enzyme catalyzed steps?(A) phosphoglucomutase (B) UDP-glucose pyrophosphorylase (C)glycogen synthase (D)amylo-(1,4→1,6)-transglycosylase(E) none of the above require energy input

43. Fatty acids are mobilized from adipose cells in response to all of the hormones EXCEPT:

(A)ACTH (adrenocorticotropic hormone).(B)glucagon.(C). insulin.(D)epinephrine (adrenaline).

(E)all are true.

44. The product of β-oxidation, acetyl-CoA, can be used for all EXCEPT: (A)synthesis of ketone bodies. (B) synthesis of amino acids. (C)catabolism in the TCA cycle. (D)synthesis of glucose. (E)none of the above.

45. The main source(s) of NADPH for fatty acid biosynthesis is (are): (A)TCA cycle. (B) oxidative phosphorylation. (C) malic enzyme and the pentose phosphate pathway. (D)the conversion of OAA to malate by malate dehydrogenase. (E)glycolysis.

46. The committed step in fatty acid biosynthesis, formation of malonyl-CoA, is catalyzed by: (A)fatty acid synthase. (B) pyruvate carboxylase. (C) propionate carboxylase. (D)acetyl-CoA carboxylase. ATP-citrate lyase.

47. Animals are totally dependent on plants and microorganisms for nitrogen fixation and nitrate assimilation because animals:(A) do not have the reducing power (NADPH) to fix nitrogen. (B) lack the enzyme aminotransferase. (C)lack the enzymes to reduce (D)lack carbamoyl-phosphate synthetase I. (E)lack glutamate dehydrogenase.

48. The involvement of ATP in the nitrogenase complex is because ATP is needed to: (A)provide electrons. (B) phosphorylate the enzyme. (C)break the N₂ triple bond. (D)transfer electrons from ferredoxin. (E)all are true.

49. Which of the following statements explains why sulfonamides are effective antibiotics? (A)serve as analogs of p-aminobenzoic acid and block bacterial synthesis of folate (B) act as inhibitors of bacterial dihydrofolate reductase, thus preventing production of tetrahydrofolate (C)act as suicide substrates for the enzyme dihydropteroate synthetase (D)do not affect humans because folate is a vitamin (E)both a and d are correct

50. What is the importance of the purine nucleoside cycle? (A)It participates in the conversion of purines into pyrimidines. (B) It generates fumarate, which inhibits the formation of AMP from IMP. (C) It provides fumarate as an anaplerotic enhancement of the citric acid cycle.(D) It inhibits the citric acid cycle in skeletal muscles. (E)It is used in energy metabolism in the liver.

110年 - 110 國立中山大學碩士暨碩士專班招生考試_生科系碩士班/乙組:生物化學#105553

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