Module General principles of metabolism Test questions in text form

Real life situation questions 
1. A competitive inhibitor of an enzyme
A. Increases Km without affecting Vmax
B. Decreases Km without affecting Vmax
C. * Increases Vmax without affecting Km
D. Decreases Vmax without affecting Km
E. All of above
2. A competitive inhibitor of an enzyme is usually:
A. A highly reactive compound
B. A metal ion such as Hg2+ or Pb2+
C. * Structurally similar to the substrate
D. Water insoluble
E. A poison
3. A holoenzyme refers to the form of the enzyme__________________.
A. * That has the cofactor attached
B. That does not have the cofactor attached
C. That is normally inactive
D. None of the above
E. That has only prosthetic group
4. A key role of the hydroxyl group at position 6 in the purine ring in the formation of a 
transition state by the enzyme adenosine deaminase is obtained by comparing a _______ 
inhibitor and a _______ inhibitor.
A. Competitive; noncompetitive
B. Transition state analog; normal substrate
C. Noncompetitive; transition state analog
D. * Competitive; transition state analog
E. All of the above
5. A molecule that has the same shape as the substrate of an enzyme would tend to
A. speed metabolism by guiding the enzyme to its substrate
B. speed metabolism because it would also be a catalyst
C. * speed metabolism by acting as a cofactor for the enzyme
D. save the cell energy by substituting for the substrate
E. slow metabolism by blocking the enzyme’s active site
6. A molecule that has the same shape as the substrate of an enzyme would tend to
A. * Speed metabolism by guiding the enzyme to its substrate
B. Speed metabolism because it would also be a catalyst
C. Speed metabolism by acting as a cofactor for the enzyme
D. Save the cell energy by substituting for the substrate
E. Slow metabolism by blocking the enzyme’s active site
7. A person having deficiency of lactase cannot digest
A. Proteins
B. * Milk
C. Starch
D. Fats
E. Potatos
8. A pseudo-first order reaction____________________.
A. Is a two substrate reaction whose rate depends on the concentration of both 
substrates

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B. * Is a single substrate reaction whose rate depends on the concentration of that 
substrate
C. Is two substrate reaction whose rate depends on the concentration of only one of 
the substrate
D. Is two substrate reaction whose rate is independent of either substrate
E. Is a complex substrate reaction whose rate depends on the concentration of that 
substrate
9. A reaction is designated as exergonic rather than endergonic when ___________.
A. Activation energy exceeds net energy release
B. Activation energy is necessary
C. No kinetic energy is released
D. * The potential energy of the products is less than the potential energy of the 
reactants
E. It absorbs more energy
10. A(n) ______ does not bind to the active site of an enzyme
A. Substrate
B. Competitive inhibitor
C. * Allosteric effector
D. A and b
E. All of the above
11. Abzymes are
A. Immuno globulins
B. Isozymes
C. * Allosteric enzymes
D. Catalytic antibodies
E. Vitamins
12. According to the second law of thermodynamics, which of the following is true?
A. The total amount of energy in the universe is constant.
B. Energy conversions increase the order in the universe.
C. * The ordering of one system depends on the disordering of another.
D. The entropy of the universe is constantly decreasing.
E. All reactions produce some heat.
13. Acyl-group-transfer reactions often involve which coenzyme?
A. * Coenzyme A
B. NAD+
C. Cytochrome c
D. All of the above
E. None of the above
14. Allosteric centers serve as:
A. * The place of influence on the enzyme different regulator factors
B. The place relation of enzyme with substrate
C. Catalytic area
D. Contact area
E. The area seperetion of the spatially united amino acid residues
15. Allosteric enzymes _____________.
A. Usually have quaternary structure.
B. Do not behave according to Michaelis-Menton kinetics.
C. * Bind allosteric modulators at sites not associated with substrate binding.
D. Often have separate catalytic and regulator domains.
E. All of the above.
16. Allosteric enzymes______________.
A. * Follow Michaelis-Menton kinetics

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B. Show hyperbolic plots when plotting [S] versus Vo
C. Are monomeric proteins
D. None of the above
E. Are oligomeric proteins
17. Among the following which is the Michaelis menten equation
A. V = Km + Vmax / (S)
B. V = Vmax ( S) / ( S) + Km
C. V = V max + (S) / (S)Km
D. V = V max (S) / Km
E. * V = V max Km/S
18. Among the following, which is the wrong statement regarding to competitive inhibition
A. * The inhibitor binds to active site of an enzyme
B. There is negligible inhibition at very high substrate concentration
C. There is an increase in Km
D. The enzyme is irreversibly inhibited by inhibitor
E. The inhibitor binds to allosteric site of an enzyme
19. An allosteric activator that affects Km but not Vmax does so by_____________.
A. Altering enzyme conformation to promote substrate binding
B. Altering enzyme conformation to increase Kcat
C. * Altering enzyme conformation to prevent binding of a competitive inhibitor
D. Altering enzyme conformation to prevent E+P
E. None of the above
20. An allosteric modulator influences enzyme activity by
A. Competing for the catalytic site with the substrate
B. * Binding to a site on the enzyme molecule distinct from the catalytic site
C. Changing the nature of the product formed
D. Covalently modifying enzyme
E. All of above
21. An enzyme is a special kind of catalyst that works to
A. * Speed up a specific biochemical reaction.
B. Slow down a chemical reaction
C. Break down chemical elements.
D. Maintain the correct temperature for a reaction
E. All answers are incorrect
22. An enzyme is specific. This means
A. It has a certain amino acid sequence
B. * It is found only in a certain place
C. It functions only under certain environmental conditions
D. It speeds up a particular chemical reaction
E. It occurs in only one type of cell
23. An enzyme without its required co-factor prosthetic group is referred to as 
the____________________.
A. Cenzyme
B. Apoenzyme
C. * Holoenzyme
D. Izoensymes
E. None of the above
24. An inhibitor binds to a site other than the active site of the enzyme. Which statement 
below correlates with this observation?
A. It must be a competitive inhibitor.
B. The inhibition must be irreversible.
C. * It could be noncompetitive or uncompetitive inhibition.

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D. It could be irreversible, competitive, noncompetitive or uncompetitive. The data 
do not relate to the type of inhibition.
E. None of above
25. An ion commonly found in metalloenzymes and which can undergo reversible oxidation 
and reduction is
A. Ca++
B. Mg++
C. S=
D. * Fe++
E. All of the above
26. An uncompetitive inhibitor binds to _____.
A. E
B. * ES
C. P
D. A and b
E. A and c
27. An uncompetitive inhibitor of an enzyme catalyzed reaction
A. * Binds to the Michaelis complex (ES)
B. Decreases Vmax.
C. Is without effect at saturating substrate concentration
D. Can actually increase reaction velocity in rare cases
E. The first and second choices are both correct
28. At the beginning of an enzyme-catalyzed reaction the _________ is negligible.
A. Formation of ES
B. * Formation of E + P
C. Conversion of ES to E + S
D. Disappearance of ES
E. Formation of ES*FES**
29. Avidin, a protein found in egg whites binds tightly to which cofactor?
A. Pyridoxal phosphate
B. * Biotin
C. thiamin pyrophophosphate
D. Lipoamide
E. NAD(P)H
30. Because coenzymes are specific for the chemical groups that they accept and donate, they 
are referred to as
A. Cofactors
B. Reactive centers
C. Activator ions
D. * Group-transfer reagents
E. All of the above
31. Both Vmax and Km values are altered in
A. Competitive inhibition
B. Noncompetitive inhibition
C. Uncompetitive inhibition
D. * All of these
E. Reversible
32. By enzymes with relative specificity can come project:
A. * Lipasa, proteases
B. Urease
C. Arginase, sucrase
D. Suktsinatdehydrogenase

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E. Alkogol dehydrogenase
33. Cleland notations are used to graphically depict _______________________.
A. Allosteric enzyme kinetics
B. The binding order of substrates and the release order of products in a 
multisubstrate reaction
C. Inhibition kinetics
D. * Michaelis Menton kinetics
E. None of the above
34. Coenzymes which must return to their original form after each catalysis are called
A. Prosthetic groups
B. Cosubstrates
C. Metabolite coenzymes
D. Vitamin coenzymes
E. * All of the above
35. Cysteine and serine residues can function in ___________ when present in the active site 
of an enzyme.
A. Anion binding
B. Cation binding
C. Proton transfer
D. * Acyl group binding
E. All of the above
36. During feedback inhibition, the allosteric site is often the __________ enzyme in the 
pathway.
A. Last
B. Least abundant
C. Most abundant
D. * First
E. Second
37. During the procedure using the turnip extract demonstrating the affect of inhibitors, what 
was the enzyme studied?
A. * Peroxidase
B. Catalase
C. Catechol oxidase
D. Hydrogen peroxide
E. Oxidoreductase
38. Enzyme cofactors that bind covalently at the active site of an enzyme are referred to as 
_________.
A. Cosubstrates
B. * Prosthetic groups
C. Apoenzymes
D. Vitamins
E. Isoenzymes
39. Enzymes
A. Enhance reaction rates
B. Are affected by pH
C. Act on specific substrates
D. Are affected by temperature
E. * All of the above
40. Enzymes fast up the velocity of a biochemical reaction by
A. * Increasing activation energy
B. Decreasing kinetic energy
C. Removing the functional group

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D. Decreasing activation energy
E. All of the above
41. Enzymes increase the velocity of a reaction by___________________.
A. * Increasing the ground state energy of the substrate by forming the ES complex
B. Stabilizing the formation of the transition state
C. Altering the equilibrium of the reaction
D. A and b
E. All of the above
42. Enzymes lower the activation energy for biochemical reactions. They do this by 
_______.
A. * Creating energy for use in the reactions they catalyze.
B. Forming a substrate-enzyme complex
C. Releasing energy which ultimately lowers the activation energy
D. Diffusion of Na and K through the Na-K pump
E. Always having a higher energy than the substrates
43. Enzymes that are activated by proteolytic cleavage are referred to as __________.
A. Covalently modified enzymes
B. Enzyme complexes
C. * Zymogens
D. Polymerized
E. Free radicals
44. Enzymes typically have _______ affinity for the substrate than for the transition state.
A. Lower
B. * Higher
C. The same
D. None of the above
E. All of the above
45. Exactly how do inhibitors affect the reaction rate of enzymes?
A. The extra energy would cause violent movement and collisions until the bonds in 
the molecule broke, causing the shape to change.
B. The high concentration of hydrogen ions (H+) would break the bonds in the 
molecule, causing the shape to change.
C. The high concentration of hydroxide ions (OH-) would break the bonds in the 
molecule, causing the shape to change.
D. * Because the inhibitor molecules are structurally similar to the substrate 
molecules, they slow down the chemical reaction.
E. The high concentration of hydrogen peroxide (H2O2) would break the bonds in 
the molecule, causing the shape to change
46. Exactly how would an extremely low pH (less than 2.0) denature an enzyme?
A. The extra energy would cause violent movement and collisions until the bonds in 
the molecule broke, causing the shape to change.
B. * The high concentration of hydrogen ions (H+) would break the bonds in the 
molecule, causing the shape to change.
C. The high concentration of hydroxide ions (OH-) would break the bonds in the 
molecule, causing the shape to change.
D. Because pH molecules are structurally similar to the substrate molecules, they 
inhibit the chemical reaction.
E. All of above
47. Glucose + ATP > Glucose -6-phosphate + ADP. This reaction is catalysed by which of 
the following enzyme classes
A. Oxidoreductase
B. * Transferase

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C. Hydrolase
D. Lyase
E. Isomerases
48. Heterolytic carbon-carbon bond cleavage can result in the formation of_____.
A. Carbocation
B. * Radical species
C. Carbanion
D. A and b
E. A and c
49. How many active centers can have enzymes?
A. 1
B. 3
C. 2
D. * Depends on the amount of subunits of enzyme
E. 10
50. If a protein is reversibly denatured, which structural level can you be sure has remained 
intact?
A. * Primary only
B. Secondary only
C. Tertiary only
D. Quaternary only
E. How sure do I have to be -?
51. If the absolute concentration of enzyme is unknown, which of the following values can 
not be determined experimentally?
A. Km
B. kcat
C. * Vmax
D. None of the above
E. All of the above
52. If the substrate concentration in an enzyme catalyzed reaction is equal to 0.5 Km, the 
initial reaction velocity will be
A. 0.25 Vmax
B. 0.33 Vmax
C. 0.50 Vmax
D. * 0.75 Vmax
E. 0. 15 Vmax
53. If the tertiary structure of an enzyme is changed _____.
A. Its substrate may not fit properly in the active site
B. It will be missing one of its polypeptides
C. * The helical coil will be stretched out
D. The product of the reaction will be a different molecule
E. Its substrate will bond covalently with the wrong part of the molecule
54. In a first order chemical reaction, the velocity of the reaction is proportionate to the 
_____, while in a zero order reaction, the velocity of the reaction is proportionate to 
_____.
A. Amount of enzyme; concentration of substrate
B. * Concentration of substrate; amount of enzyme
C. Concentration of substrate; the speed of the reaction
D. The speed of the reaction; concentration of substrate
E. All of the above
55. In an enzyme reaction involving one enzyme and one substrate, the rate of the reaction 
depends on

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A. Substrate concentration
B. Enzyme concentration
C. * Both substrate and enzyme concentrations
D. The enzyme concentration at first and the substrate concentration later on
E. Speed of reaction
56. In describing enzyme feature, enzymes:
A. Are composed primarily of polypeptides, which are polymers of amino acids
B. Can bind prosthetic groups such as metal ions that participate in enzyme reactions
C. Have defined structures.
D. * Bind their substrates at active sites
E. All statements are true
57. In describing the reaction rate for a chemical reaction, which of the following statements 
about reaction rate is NOT true?
A. Reaction rate is the speed at which the reaction proceeds toward equilibrium.
B. * Reaction rate is governed by the energy barrier between reactions and products
C. Enzymes can accelerate the rate of a reaction
D. Reaction rates are not sensitive to temperature.
E. None of these
58. In formation of temporal complex between an enzyme and substrate important role 
belongs chemical bonds, except:
A. Disulfide
B. Ion
C. * Peptid
D. Hydrogen bonds
E. Hydrophobic interaction
59. In understanding activation energy, activation energy is
A. * Energy that must be added to get a reaction started, which is recovered as the 
reaction proceeds
B. Difference in energy between reactants and products
C. Energy that is lost as heat.
D. Free energy
E. Equal to the entropy times the absolute temperature
60. In which of the following do both examples illustrate kinetic energy?
A. * Positions of electrons in an atoma ball rolling down hill
B. Heatarrangement of atoms in a molecule
C. A rock resting on the edge of a cliffheat
D. A ball rolling down a hillheat
E. Lightarrangement of atoms in a molecule
61. In which of the following do both examples illustrate kinetic energy?
A. Positions of electrons in an atoma ball rolling down hill
B. Heatarrangement of atoms in a molecule
C. * A rock resting on the edge of a cliffheat
D. A ball rolling down a hillheat
E. Lightarrangement of atoms in a molecule
62. is known as _________ inhibition.
A. * Competitive
B. Uncompetitive
C. Uncompetitive
D. Feedback
E. Allosteric
63. Isoenzymes are generally separated by
A. Ion exchange chromatography

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B. Gel filtration chromatography
C. Paper chromatography
D. * Electrophoresis
E. Selective adsorbtion
64. Km is _______.
A. The substrate concentration at ? Vmax.
B. = (k-1 + kcat)/k1
C. Related to an enzymes affinity for a specific substrate.
D. * The Michaelis Constant
E. All of the above
65. Km values are not altered by which type of inhibitor
A. * Competitive inhibitors
B. Non competitive inhibitors
C. Uncompetitive inhibitors
D. Allosteric inhibitor
E. All of these
66. Lactate dehydrogenase is a
A. Coenzyme
B. * Isoenzyme
C. Zymogen
D. Abzyme
E. Prostetic group
67. Michaelis constant Km is
A. Dependent on enzyme concentration
B. Independent of Ph
C. * Equal to substrate concentration that gives half Vmax
D. Numerically equal to half Vmax
E. Dependent on substrate concentration
68. Minerals and metals are often used in or as
A. Enzymes and coenzymes
B. * Coenzymes and cofactors
C. Cofactors and prosthetic groups
D. Coenzymes and prosthetic group
E. Prizes in the subcellular Olympics
69. Molybdenum is present in
A. Carboxypeptidase
B. Dinitrogenase
C. Pyruvate dehydrogenase
D. Pyruvate carboxylases
E. * Xantinoxidase
70. Most enzymes are composed of.
A. Lipids
B. Carbohydrates
C. * Proteins
D. Phosphates
E. Vitamins
71. Most enzymes are composed of.
A. Lipids
B. Carbohydrates
C. * Proteins
D. Phosphates
E. Vitamins

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72. Name of enzyme which include zinc?
A. * Alkohol dehydrogenase
B. Cytochromoxidase
C. Xantinoksidase
D. Pyruvate dehydrogenase
E. Lactate dehydrogenase
73. Nicotinamide is ____________.
A. A co-substrate
B. A metabolite coenzyme
C. * A vitamin
D. A prosthetic group
E. None of the above
74. Noncompetitive inhibitor binds with
A. Active site
B. Allosteric site
C. Enzyme substrate complex
D. * Substrate
E. Product of reaction
75. Pyridoxal phosphate is involved in which type of reaction?
A. Oxidation of pyruvate
B. * Production of new amino acids by transamination
C. Phosphate-transfer to produce ATP from ADP
D. The regeneration of methionine from homocysteine
E. None of the above
76. Reaction order describes which of the following.
A. The order that substrates bind to the enzyme.
B. The order of reactions in a biosynthetic pathway
C. * How the velocity of a reaction is dependent on the concentration of specific 
reactants.
D. All of the above
E. A and c
77. Role of coenzymes can active part vitaminesimillar substens. What matters does not act