1) Which of the following best describes a metastable state?
A) The metastable state is a state of the substrate in which the
reaction can proceed but typically requires a catalyst.
B) The metastable state is formed by transient complexes with the substrate.
C) This state changes the position of the equilibrium but not the rate.
D) This state is composed of the difference in activation energy of
a catalyzed versus an uncatalyzed reaction.
E) The metastable
state is created by the prosthetic group of the enzyme.
A
2) The work of James B. Sumner was to
A) originate the
term ferments to describe enzymes.
B) crystallize urease, the first enzyme isolated.
C) prove that enzymes were carbohydrates.
D) discover ribozymes.
E) isolate the insulin hormone.
B
3) An enzyme
A) decreases the rate of a reaction.
B) is always a protein.
C) does not change the rate at which the equilibrium is achieved.
D) binds substrates in a manner that facilitates the formation of product.
E) changes the position of the equilibrium of the reaction.
D
4) The site on an enzyme that will bind the substrate is called
the
A) catalyst.
B) activation site.
C)
metastable site.
D) active site.
E) prosthetic group.
D
5) Which of the following is an example of a prosthetic group?
A) a nickel catalyst
B) a zinc ion
C) carboxypeptidase
A
D) a glycine residue
E) a polypeptide chain
B
6) Which of the following is an enzyme?
A) histidine
B) ATP
C) iron
D) N-acetylmuramic
acid
E) carboxypeptidase A
E
7) All of the following are examples of irreversible enzyme
inhibitors except
A) herbicides.
B) natural poisons.
C) monoamine
oxidase inhibitors.
D) aspirin.
E) pesticides.
C
8) As new enzymes are discovered, the EC system for naming enzymes is
to be used. The names are to be based on which of the following criteria?
A) a description of substrate function
B) an indication of
the size of the substrate
C) the six major classes of enzyme
function
D) the name of the substrate
E) the size of the enzyme
A
9) The active site for carboxypeptidase
A) is formed by the interaction of two polypeptide
chains.
B) involves only 6 out of a total of 307 amino
acids.
C) uses iron as the prosthetic group.
D) contains a
glutamate residue at position 69.
E) contains amino acids that
are contiguous to one another along the primary sequence of the
protein.
B
10) According to the EC system, which is not one of the major groups
of enzymes?
A) hydrolases
B) proteases
C) oxidoreductases
D)
ligases
E) transferases
B
11) An enzyme is active in the stomach of an animal but quickly loses
its activity when it leaves the stomach. This example illustrates that
enzymes are
A) sensitive to changes in pH.
B) consumed by the
quantities of substrate in the small intestine.
C) inactivated by
movement.
D) specific to the organs in which they are
produced.
E) inactivated by inhibitors in the small intestine.
A
12) A sick person often has a fever, which can inhibit the growth of
bacteria because
A) sweating removes prosthetic groups from biological
enzymes.
B) fever blocks synthesis of proteins in the bacterial
nucleus.
C) bacteria reproduce more rapidly at higher body
temperature.
D) the higher temperature increases the activity of
lyases.
E) enzymes do not function as well at temperatures other
than the optimal temperature.e
E
13) An organism that is labeled a cryophile is capable of
A) synthesizing liquid nitrogen.
B) producing large
quantities of liquid hydrogen.
C) growth in hydrothermal
vents.
D) growth at 4°C.
E) both choices C and D
D
14) The equation AB + H2O → A + B would be catalyzed by which of the
following classes of enzymes?
A) oxidoreductases
B) isomerases
C) ligases
D)
transferases
E) hydrolases
E
15) The equation A-PO4 + B → A + B-PO4 would be catalyzed by which of
the following classes of
enzymes?
A) transferases
B) oxidoreductases
C) ligases
D)
isomerases
E) hydrolases
A
16) Substrate activation may involve
A) accepting protons from the enzyme.
B) formation of
temporary covalent bonds.
C) donation of protons to the
enzyme.
D) a change in enzyme conformation induced by substrate
binding.
E) all of the above
E
17) An enzyme influences the structure of which of the following?
A) substrate
B) intermediate
C) cofactor
D)
product
E) transition state
E
18) A competitive inhibitor will affect the ________ of an enzymatic reaction.
A) V max
B) P
C) K m
D) S
E) b oth choices A
and B
C
19) A noncompetitive inhibitor will affect the ________ of an
enzymatic reaction.
A) P
B) K m
C) V max
D) S
E) both choices A
and B
C
20) The type of inhibitor that binds to the enzyme (E) but not to the
enzyme-substrate (ES) complex
is a(n) ________ inhibitor.
A) uncompetitive
B) competitive
C) mixed-type
D)
noncompetitive
E) coenzyme
B
21) Why is the Lineweaver—Burk plot important in enzyme kinetics?
A) It makes it easier to determine Vmax.
B) It is a
single-reciprocal plot.
C) It is nonlinear.
D) It
illustrates enzyme specificity.
E) It reveals the presence of
prosthetic groups in enzymes.
A
22) The Michaelis constant
A) is equal to the substrate concentration at Vmax/2.
B) is
equal to twice the Vmax.
C) can be determined using the
Lineweaver—Burk plot.
D) both choices A and C
E) choices A,
B, and C
D
23) Saturation can be defined as
A) inhibition of enzyme function by blocking the active
site.
B) the substrate concentration at which velocity reaches
one-half maximum velocity.
C) the inability to increase reaction
velocity beyond a finite upper limit.
D) acharacteristic of all
uncatalyzed reactions.
E) denaturation of an enzyme.
C
24) The equation v = Vmax [S]/(Km + [S]) is part of which of the
following plots?
A) Eadie—Hofstee
B) Michaelis—Menten
C)
Lineweaver—Burk
D) both choices A and B
E) n one of the above
B
25) An allosteric inhibitor
A) binds at the regulatory site.
B) is converted to an
activator by the enzyme.
C) is identical to the active
site.
D) binds and activates the high-affinity state of the
enzymes.
E) increases the rate of substrate binding.
A
26) A competitive inhibitor
A) irreversibly binds and inactivates the enzyme.
B) binds
at a site other than the active site.
C) cannot be processed by
the enzyme.
D) does not inhibit enzyme activity but does lower
substrate concentration.
E) binds to and inactivates the substrate.
C
27) An example of an irreversible inhibitor is
A) acetylcholinesterase.
B) a competitive
inhibitor.
C) isoleucine.
D) penicillin.
E) a
noncompetitive inhibitor.
D
28) Covalent modification
A) can activate an enzyme.
B) can involve the addition of
phosphate groups.
C) affects the activity of an enzyme by adding
or removing a chemical group.
D) produces modifications that can
sometimes be reversed.
E) all of the above
E
29) Which of the following is/are means whereby a catalyst can lower
the activation energy of a reaction?
A) decreasing the number of reactive molecules
B)
inefficient collisions
C) altering the temperature within the
cell to one appropriate for reactions to proceed
D) permanently
binding substrates
E) quantum tunneling
E
30) Of the following, which is used to inhibit specific enzymes in
the treatment of many bacterial
and viral diseases?
A) intercalating agents
B) nitrous oxide
C)
X-rays
D) substrate analogues
E) noncompetitive inhibitors
D
31) A noncompetitive inhibitor will
A) bind to free enzyme.
B) decrease Vmax.
C) decrease
Km.
D) bind to free product.
E) both choices A and C
B