Multiple Lehninger Biochemistry
Chapter 6 Choice
One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under
conditions of zinc deficiency, when the enzyme may lack zinc, it would be referred to as
the:
A) apoenzyme.
B) coenzyme.
C) holoenzyme.
D) prosthetic group.
E) substrate. - answersA) apoenzyme.
Which one of the following is not among the six internationally accepted classes of
enzymes?
A) Hydrolases
B) Ligases
C) Oxidoreductases
D) Polymerases
E) Transferases - answersD) Polymerases
Enzymes are potent catalysts because they:
A) are consumed in the reactions they catalyze.
B) are very specific and can prevent the conversion of products back to substrates.
C) drive reactions to completion while other catalysts drive reactions to equilibrium.
D) increase the equilibrium constants for the reactions they catalyze.
E) lower the activation energy for the reactions they catalyze. - answersE) lower the
activation energy for the reactions they catalyze.
The role of an enzyme in an enzyme-catalyzed reaction is to:
A) bind a transition state intermediate, such that it cannot be converted back to
substrate.
B) ensure that all of the substrate is converted to product.
C) ensure that the product is more stable than the substrate.
D) increase the rate at which substrate is converted into product.
E) make the free-energy change for the reaction more favorable. - answersD) increase
the rate at which substrate is converted into product.
, Which one of the following statements is true of enzyme catalysts?
A) Their catalytic activity is independent of pH.
B) They are generally equally active on D and L isomers of a given substrate.
C) They can increase the equilibrium constant for a given reaction by a thousand fold or
more.
D) They can increase the reaction rate for a given reaction by a thousand-fold or more.
E) To be effective, they must be present at the same concentration as their substrate. -
answersD) They can increase the reaction rate for a given reaction by a thousand-fold
or more.
Which one of the following statements is true of enzyme catalysts?
A) They bind to substrates but are never covalently attached to substrate or product.
B) They increase the equilibrium constant for a reaction, thus favoring product
formation.
C) They increase the stability of the product of a desired reaction by allowing
ionizations, resonance, and isomerizations not normally available to substrates.
D) They lower the activation energy for the conversion of substrate to product.
E) To be effective, they must be present at the same concentration as their substrates. -
answersD) They lower the activation energy for the conversion of substrate to product.
Which of the following statements is false?
A) A reaction may not occur at a detectable rate even though it has a favorable
equilibrium.
B) After a reaction, the enzyme involved becomes available to catalyze the reaction
again.
C) For S P, a catalyst shifts the reaction equilibrium to the right.
D) Lowering the temperature of a reaction will lower the reaction rate.
E) Substrate binds to an enzyme's active site. - answersC) For S P, a catalyst shifts the
reaction equilibrium to the right.
Enzymes differ from other catalysts in that only enzymes:
A) are not consumed in the reaction.
B) display specificity toward a single reactant.
C) fail to influence the equilibrium point of the reaction.
D) form an activated complex with the reactants.
E) lower the activation energy of the reaction catalyzed. - answersB) display specificity
toward a single reactant.
Compare the two reaction coordinate diagrams below and select the answer that
correctly describes their relationship. In each case, the single intermediate is the ES
complex.
Chapter 6 Choice
One of the enzymes involved in glycolysis, aldolase, requires Zn2+ for catalysis. Under
conditions of zinc deficiency, when the enzyme may lack zinc, it would be referred to as
the:
A) apoenzyme.
B) coenzyme.
C) holoenzyme.
D) prosthetic group.
E) substrate. - answersA) apoenzyme.
Which one of the following is not among the six internationally accepted classes of
enzymes?
A) Hydrolases
B) Ligases
C) Oxidoreductases
D) Polymerases
E) Transferases - answersD) Polymerases
Enzymes are potent catalysts because they:
A) are consumed in the reactions they catalyze.
B) are very specific and can prevent the conversion of products back to substrates.
C) drive reactions to completion while other catalysts drive reactions to equilibrium.
D) increase the equilibrium constants for the reactions they catalyze.
E) lower the activation energy for the reactions they catalyze. - answersE) lower the
activation energy for the reactions they catalyze.
The role of an enzyme in an enzyme-catalyzed reaction is to:
A) bind a transition state intermediate, such that it cannot be converted back to
substrate.
B) ensure that all of the substrate is converted to product.
C) ensure that the product is more stable than the substrate.
D) increase the rate at which substrate is converted into product.
E) make the free-energy change for the reaction more favorable. - answersD) increase
the rate at which substrate is converted into product.
, Which one of the following statements is true of enzyme catalysts?
A) Their catalytic activity is independent of pH.
B) They are generally equally active on D and L isomers of a given substrate.
C) They can increase the equilibrium constant for a given reaction by a thousand fold or
more.
D) They can increase the reaction rate for a given reaction by a thousand-fold or more.
E) To be effective, they must be present at the same concentration as their substrate. -
answersD) They can increase the reaction rate for a given reaction by a thousand-fold
or more.
Which one of the following statements is true of enzyme catalysts?
A) They bind to substrates but are never covalently attached to substrate or product.
B) They increase the equilibrium constant for a reaction, thus favoring product
formation.
C) They increase the stability of the product of a desired reaction by allowing
ionizations, resonance, and isomerizations not normally available to substrates.
D) They lower the activation energy for the conversion of substrate to product.
E) To be effective, they must be present at the same concentration as their substrates. -
answersD) They lower the activation energy for the conversion of substrate to product.
Which of the following statements is false?
A) A reaction may not occur at a detectable rate even though it has a favorable
equilibrium.
B) After a reaction, the enzyme involved becomes available to catalyze the reaction
again.
C) For S P, a catalyst shifts the reaction equilibrium to the right.
D) Lowering the temperature of a reaction will lower the reaction rate.
E) Substrate binds to an enzyme's active site. - answersC) For S P, a catalyst shifts the
reaction equilibrium to the right.
Enzymes differ from other catalysts in that only enzymes:
A) are not consumed in the reaction.
B) display specificity toward a single reactant.
C) fail to influence the equilibrium point of the reaction.
D) form an activated complex with the reactants.
E) lower the activation energy of the reaction catalyzed. - answersB) display specificity
toward a single reactant.
Compare the two reaction coordinate diagrams below and select the answer that
correctly describes their relationship. In each case, the single intermediate is the ES
complex.
