生化出题092

生化出题生物092 酶、维生素
3.The k cat of carbonicanhydrase is 106 s-1,while the k cat of catalase is 107s-1. Which is more efficient in catalyzing reactions?_____
A.Carbonic anhydrase.
B. Catalase.
C. There is not enough information to make a conclusion.
D. They are same.
4.Which reaction is not multisubstrate reaction? _____
A.Random reaction
B.Ordered reaction
C.Ping-pang reaction
petitive reaction
5.Which describe about ping-pang reaction is right? _____
A. The altered enzyme is restored to its original form before second product is bound.
B. The altered enzyme is restored to its original form before the first product is released.
C. The first product is released after which the second substrate is bound.
D. The first product is released before which the second substrate is bound.
6. Which description about sequential reaction is not right?_____
A.ordered reaction is a kind of sequential reaction.
B. random reaction is a kind of sequential reaction.
C. sequential reaction requires all the substrates to be present before any product is released.
D.sequential reaction requires all the substrates to be present after any product is released.
7.When a competitive inhibitor is bound to an enzyme molecule,how will V max and K m change?_____
A. V max remains unchanged, K m increases
B. V max decreases,K m decreases
C. V max remains unchanged, K m decreases
D. V max decreases,K m increases
8. Which of the following is wrong?_____
A. Reversible enzyme inhibition includes competitive inhibition、uncompetitive inhibition、noncompetitive inhibition
B. Dialysis method can identify reversible inhibition
C. Cofactor or coenzyme can contribute to a variety of enzyme activity
D. Remove the cofactor or coenzyme the enzyme will be denatured protein inactivation
9. Which is the characteristic of competitive inhibition?_____
A. Inhibitors have a similar structure with the substrate
B. The combination of inhibitor binding does not affect the substrate
C. V max decreases
D. K m remains unchanged
10. Which statement about isoenzyme is right?_____
A. They have the same catalytic reaction
B. They have the same molecular structure
C. They have the same immunological properties
D. They have the same kinetic parameters
11. Which statement about allosteric enzyme is wrong?_____
A. Allosteric enzymes can change the activity of enzymes
B. Allosteric enzymes can be combined with the catalytic part ofenzymes
C. Allosteric enzymes can reversible binding with the enzyme molecules
D. Allosteric enzymes can change the conformation of the enzymes
12. Zymogen is inactive because
A. Active center is not formed or exposed
B. Zymogen is nomal protein
C. Lack of coenzymes or cofactors
D. Zymogen is denatured protein
13. Organophosphorus pesticides as inhibitors of the enzyme is acting on _____part of the enzyme active center.
A. Sulfhydryl
B. Hydroxyl
C. Carboxyl
D. Imidazole
14. What is the physiological meaning of zymogen activation?_____
A. Speed up the metabolism.
B. Restore the activity of enzymes.
C. The way of biological self-protection.
D. The way of protecting enzymes.
15. Zymogen is the precursor of enzymes _____
A. It has activity.
B.I t hasn’t activity.
C. It can increase activity.
D. It can decrease activity.
16. Allosteric enzyme is_____
A. Monomeric enzyme
B. Oligomeric enzyme
C. Multienzyme complex
D. Michaelis enzyme
17.The most recognized theory about enzyme and substrate binding is?_____
A. Theory of the active center
B. Induced fit theory
C. Lock-key theory
D. Intermediate theory
18.Many chemical reactions have ionic intermediates. There are two types of ionic intermediates：One species is electron-rich ，or____B___, and the other species is electron-poor , or ____A___.
A.Electrophilic
B.Nucleophilic
C.Cleavage reaction
D.Oxidation-reduction reactions
19.Another type of nucleophilic substitution involves direct displacement. In this mechanism ,the attacking group or molecule adds to the face of the central atom opposite the leaving group to form a ________having five groups associated with the central atom.
A. Oxidation state
B. Reduction state
C. Transition state
D. Equilibrium state
20.This is an example of a ___________ reaction.
A .Nucleophilic substitution
B .Electrophilic substitution
C .Oxidation
D. Reduction
21 .Which effects will happen in enzymatic reaction?_____
A. Raise energy levels of products.
B. Reduce activation energy of the reactions.
C. Raise activation energy needed to start reactions.
D. Reduce energy levels of reactants.
22. Which of the following ones supports induced-fit theory?_____
A. The relationship between enzyme and substrate is same as it between lock and key.
B. Enzyme active center is variable, only when the spatial structure of it changes under the influence of substrate, could reactions happen.
C. Conformation of the enzyme does not change but the structure of substrate changes for adapting into enzyme active center.
D. Substrate analogues cannot induce the change of enzyme’s conformation.
23. The correct statement of enzyme inhibitor is_____
A. Enzyme inhibitors are enzyme denaturants.
B. Enzyme denaturants only can combine with the genes of enzyme active center.
C.All the enzyme denaturants can reduce the speed of enzymatic reaction.
D. Generally, enzyme inhibitors are macromolecules.
24.Which two modes of enzymatic catalysis invoveionizable side chains? (Which two modes are chemical modes of enzymatic catalysis?) _____
1.induced-fit
2.acid-base catalysis
3.proximity effect
4.covalent catalysis
A.1 2
B.3 4
C.1 3
D.2 4
25.Which sentence is uncorrect about covalent catalysis?_____
A. A substrates is bound covalently to the enzyme to form a reactive intermediate.
B. Ionizable side chains participate in this kinds of catalysis.
C. The acceleration of a reaction is achieved by catalytic transfer of a proton.
D. The reacting side chain of the enzyme can be either a nucleophile or an electrophile.
26.Which sentence about chemical mode of enzymatic catalysis is wrong?_____
A. Enzymes that employ acid-base catalysis have amino acid side chains that can donate and accept protons.
B. The major modes of enzymatic catalysis are acid-base catalysis and induct-fit.
C. The effects of pH on the rate of an enzymatic reaction can suggest which residues paticipate in catalysis.
D. Inidazoliums(咪唑基) on histidine are the most active group in acid-base catalysis.
27. Which step is the rate-determining step of a typical enzyme catalyzed reaction? _____
A. Binding of substrates
B. Chemical catalysis
C. Both A&B
D. Neither A nor B
28.Which type of chemical reaction CANNOT proceed a higher rate?___
A. Association reaction.
B. Proton transfers.
C. Electron transfers.
D. Covalent binding reaction.
29.Superoxide Dismutase has a rate exceeds the rate of diffusion reaction because of _____
A. Binding of the anionic substrate.
B. Transfer of electron & proton.
C. Electrostatic effect.
D. Release of uncharged products.
30.What determine the substrate specificity of reactions? _____
A. The chemical properties of an enzyme and the shape of the amino acid residues.
B. The chemical properties of the amino acid residues and the shape of the active site of an enzyme.
C. The temperature of reactions.
D. The solution composition.
31.Which one below does not influence the degree of binding of substrates to enzymes?_____
A. Mechanic reasoning.
B. Measurements of the tightness of binding of substrates.
C. Inhibitors to enzymes.
D. The temperature of reactions.
32.What an enzyme must be complementary to the transition state ?__
A. In shape and chemical character
B. In size
C. In molecular polarity
D. In molecular charging
33. Which one is correct in the following statement?_____
A .The response in solution between two reactants is intramolecular reaction.
B .In a system,if the confusion degrees is higher,the entropy would be lower.
C .The intramolecularreaction involves true catalysis.
D .In the intramolecular reactions, the substrate was covalently attached to the catalyst, and there was no recycling of the catalyst.
34. Which one has two bonds that allow rotational freedom?____
A. Glutarate ester.
B. Succinate ester.
C. The rigid bicyclic compound 4.
D. None.
35. In the compound,the interaction between enzymes and the object including_____
A. Hydrogen bond \Ion key\van der Waals force \hydrophobicity
B. Hydrophobicity\Ion key\van der
C. Van der Waals force\ Hydrogen bond\ hydrophobicity
D. Ion key\van der Waals force \hydrophobicity
36. Which of the following is wrong .
A. Induced-fit is not a catalytic mode but primarily a substrate specificity effect.
B.Enzymes are rigid templates that accepted only certain substrates as keys.
C.The transition state is a stable high-energy state.
D.An enzyme is most effective if it is in the active form initially.
37. What is not the factor to affect the efficiency of enzymatic catalysis?_
A. Induced fit.
B. Covalent catalysis.
C. The proximity effect.
D. Active center.
38. Which of the following is electrophilic base ? .
A. Imidazolyl
B. Hydrosulphonyl
C. Metallic ion
D. Hydroxyl
39. The experiment that examines the mechanism of chymotrypsin should be in ____ environment
A. A hydrophobic environment.
B. A hydrophilic environment.
C. An acid environment.
D. An alkalic environment.
40. A proposed detailed mechanism for chymotryspin includes _____kind(s) of chemical catalysis?
A. Covalent catalysis
B. Acid-base catalysis
C. Both
D. Neither
41. How to assess the relative importance of the amino acids in the Ser-His-Asp catalytic triad in the chymotrypsin and other serine proteases?_____
A. Site-directed mutagenesis
B. X-ray crystallography
C. Covalent modification
D. Allosteric regulation
42. The serine proteases typsin, chymotrypsin, and elastase catalyze much of the digestion of peptides in the _____
A. Mouth cavity
B. Stomach
C. Intestine
D. All of above
43. The serine proteases are initially synthesized and stored in the pancreas as
_____called zymogen.
A. Active precursors
B. Inactive precursors
C. Selective proteolysis
D. Serine residue
44. Experiments with specifically mutated trypsin indicate that the ____at the base of its specificity pocket is a major factor in substrate specificity.
A. Asp residue
B. Glu residue
C. Ser residue
D. Met residue
45. Serine proteases are a class of enzymes that _____in the protein.A. Cleave the disulfide bonds
B. Cleave the peptide bond
C. Both a and b
D. Neither a nor b
46.Cosubstrates——one type of coenzymes,are actually substrates in
enzyme-catalyzed reactions, which of the followings about it is false？__
A. The cosubstrate is part of active site.
B.It is recycled repeatedly within the cell.
C.Coenzymes shuttle mobile metabolic groups among different enzymes-catalyzed reactions.
D.It remains bound to the enzyme during the course of the reaction.
47. Metalloenzyme is a kind of enzyme that requires metallic cations to achieve full catalytic activity, which of the followings about it is false？_
A. It contains firmly bound metal ions at their active site.
B. The ions of some metalloenzymes can act as eletrophilic catalysis.
C. The ions of some metalloenzymes can undergo reversible oxidation and reduction.
D.Metal-actived enzymes belong to metalloenzymes.
48. Cofactors can be classified into_____
A. Metalloenzymes and coenzymes
B. Essential ions and metalloenzymes
C. Prosthetic groups and essential ions
D. Prosthetic groups and coenzymes
49. When one ATP hydrolyzes completely,we can get _____
A. One ribose,one adenine,three phosphoric acids.
B. One deoxyribose, one adenine,three phosphoric acids.
C. One ribose,one adenosine,three phosphoric acids.
D. One deoxyribose, one adenosine,three phosphoric acids.
50. NAD+ and NADH are the coenzymes of_____
A.Dehydrogenases
B. Acyltransferase
C. Transaminase
D. Decarboxylase
51. The role of NAD+ and NADH is to transfer_____
A. Two hydrogen atoms
B. One hydride ion
C.Amino
D. Acyl
52. Where are the FAD and FMN derived from?_____
A. Vitamin B1
B. Vitamin B2
C. Vitamin B3
D. Vitamin B5
53. What’s the reactive center of CoA?_____
A. —SH
B. —OH
C. —CH3
D. —NH2
54. Which is involved in acyl-group-transfer reactions in which simple carboxylic
acids and fatty acids are the mobile metabolic groups?_____
A、TPP
B、FAD / FADH2
C、CoA
D、FAD / FADH2
55.Which vitamin is the composition of TPP ?_____
A.B1
B.B2
C.B3
D.B4
56. Pyridoxal phosphate is a kind of coenzyme formed by?_____
A.B3
B.B4
C.B5
D.B6
57.Which radical is biotin catalyzed and transported？_____
A. Hydroxide
B. Carboxyl
C. Aldehyde
D. Ketone
58. Tetrahydrofolate is formed from folate by adding hydrogen to positions of the pterin ring system except_____
A. 5
B. 6
C. 7
D. 9
59. Tetrahydrofolate is required by enzymes that catalyze biochemical transfers of how many carbon units?_____
A. 1
B. 2
C. 3
D. none of above
60. Cobalamin is required as a micronutrient by the following organisms except_____
A. bacteria
B. algae
C. all animals
D. plants
61.In order to well absorb Vitanmin A by intestine from carrots, you'd better to cook it by _____ .
A. Aldehyde
B. Carboxylic acid
C. Oil
D. Water
62.Which of following is the most slowly diffused agent in the silica gel column chromatography with weak polar mobile phase?_____
A.Vitamin C
B.Vitamin D
C.Vitamin E
D.Vitamin K
63.Which of following agents is the strongest reducing lipid vitamins in biological pathways?_____
A.Vitamin A
B.Vitamin C
C.Vitamin E
D. Vitamin K
64. Which one plays the major role in membrane-associated electron transport?_____
A.ATP
B.FADH2
C. Coenzyme Q
D.NADH
65. Which description of protein coenzyme is false?_____
A. They do not catalyze reactions by themselves.
B. They are generally less heat-stable than most enzymes.
C. They can only participate in reactions with certain enzymes.
D. They are smaller than enzymes.
66. Which of the following names is not one of the categorizes enzymes classified according to the general class of organic chemical reaction that is catalyzed?_____
A. Urease
B. Transferase
C. Hydrolase
D.Ligase
67. Which kind of enzyme catalyzes the reaction requiring the presence of coenzymes?_____
A. Kianase
B. Oxidoreducate
C. Lyase
D. Transferase
68. Which of the following statement is incorrect?_____
A. In group-transfer reactions, substrates and enzymes are connected with covalent binds.
B. Hydrolases are a special class of transferases with water serving as the acceptor of the group transferred.
C.The enzyme catalyzing the interconversion of L-alanine and D-alanine is one of Isomerases.
D. Since the enzymes catalyze both forward and reverse reactions, two-way arrows are used even when then equilibrium favors a great excess of producy over substrate.
69. Which of the following coenzymes are the coenzyme of decarboxylase?_____
A.NAD+
B.FAD
C.NADH
D.TPP
70. Please choose the wrong statement._____
A.NAD+ is the oxidation state of NADH.
B.FMN/FMNH2 can transfer two hydrogen atoms.
C.NADP+/NADPH are the coenzymes of dehydrogenase.
D.CoA is the coenzyme of aminotransferase.
71. CoQcan transfer_____
A. Hydrogen atom
B. Electron
C. Hydrogen atom and electron
D. Hydrogen ion
72.The enzymatic reaction _____
A. Can decrease ΔG0
B. Can increase the energy of ES
C. Cannot change ΔG0 but change the rate of product and substrate.
D.Accelerate the velocity of both forward reaction and backward reaction
73. Which of the following demonstrations about the enzyme-substrate complex is not true? _____
A. The stabilize of enzyme will increase when enzyme binds substrate.
B. When the concentration of substrate reaches a certain high level, the catalytic center of an enzyme will be saturated and the velocity will be maximal.
C. Due to the rapid response of substrate, it is unable to separate the ES.
D. ES can be analysed by the X-ray crystal diffraction.
74. Which of the following groups of enzyme is not included in the six categories which is maintained by the IUBMB(the International Union of Biochemistry and Molecular Biology )?_____
A. Oxidoreductases
B. Transferases
C. Lyases
D. Ttypsin
75. When the concentration of substrate is much larger than the amount of enzyme, the greatest impact on the reaction rate reaction is ________of the following reaction.
A.ES−−−−→E+P
B. E+S−−−−→E+P
C. E+S−−−−→ES
D. non above
76. When the concentration of substrate is much larger than the amount of enzyme, the kinetic of the reaction is____.
A. K cat
B. K m
C. K cat/K m
D. K m/K cat
77. 10 µmol of enzyme catalytic 100 µmol of substrate in 5 minute，how many enzyme a catalytic constant?_____
A.0.5µmol
B.5µmol
C.50µmol
D.500µmol
1. A
2. C
3. B
4. D Multisubstrate reactions cotain :1. Sequential reactions which contains
ordered reactions and random reactions 2. ping-pong reactions.
原版教材P142
5. C 在乒乓反应中，第二个底物B与酶结合之前，第一个底物A已转变成产
物P并被释放，在此过程中无三元复合体，反应物与产物“一进一出”。

原版教材P142
6. D 原版教材P142 第一段正数第10行
7. A
8. D
9.WEIZHI
10.A
11.B
12.A
13.B
14.C
15.B
16.B
17.B
18.B A 原版教材159页
19.C Transition state is an unstable, high-energy state.It has a structure between
that of the reactant and that of the product. 原版教材159页
20.A 原版教材159页
21.B
22.B
23.C
24.D
25.C
26.B
27.B
28.D
29.C
30.B
31.D
32.A
33.D
34.A
35.A
36.C
37.D
38.C
39.A
40.C
41.A
42.C P182 paragraph 5 line 1
43.B P182 paragraph 5 line 2
44.A P183 paragraph 3 line 13
45.B P182 paragraph 2 line 1
46.D
47.D
48.D
49.A
50.A
51.B
52.B
53.A
54.C
55.A
56.D
57.B
58.D P208 7.10 倒数第三行
59.A P209 7.10 倒数第二行
60.D P211 7.11 正数第二行
61.C
62.A
63.C
64.C
65.B
66.A P131-2
67.D P131-4
68.D P132-4
69.D
70.D
71.C
72.D 出自生化辅导书练习第一题
73.C 出自生化辅导书练习第二题
74.D 出自生化课本P131关于酶分类的考察
75.A
76.A
77.A。