Question 1

Penicillin is an antibiotic that kills bacteria by binding to the active site of an enzyme involved in synthesis of the bacterial cell wall. Which of the following phenomena best describes the mechanism of action of penicillin?

Accepted Answer

A)   noncompetitive inhibition
B)   feedback inhibition
C)   allosteric regulation
D)   competitive inhibitionE) B) and D)
F) B) and C)

Question 2

Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones?

Accepted Answer

A)   catabolism (catabolic pathways) 
B)   metabolism
C)   anabolism (anabolic pathways) 
D)   dehydrationE) C) and D)
F) B) and C)

Question 3

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

Accepted Answer

A)   by binding to the active site of the enzyme, thus preventing binding of the normal substrate
B)   by binding to an allosteric site, thus changing the shape of the active site of the enzyme
C)   by decreasing the free-energy change of the reaction catalyzed by the enzyme
D)   by increasing the activation energy of the reactionE) A) and B)
F) A) and C)

Question 4

When ATP is hydrolyzed to activate a target protein, what is often the fate of the inorganic phosphate that is released?

Accepted Answer

A)   It is secreted as waste.
B)   It is always used to regenerate more ATP.
C)   It may be used to form a phosphorylated intermediate.
D)   It enters the nucleus to be incorporated in a nucleotide.E) B) and C)
F) B) and D)

Question 5

Which of the following statements best describes metabolism in its entirety in all organisms?

Accepted Answer

A)   Metabolism depends on a constant supply of energy from food.
B)   Metabolism uses all of an organism's resources.
C)   Metabolism consists of all the energy transformation reactions in an organism.
D)   Metabolism manages the increase of entropy in an organism.E) B) and D)
F) A) and B)

Question 6

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to ________.

Accepted Answer

A)   add more of the enzyme
B)   heat the solution to 90°C
C)   add more substrate
D)   add a noncompetitive inhibitorE) B) and C)
F) All of the above

Question 7

Zinc is an essential trace element for most organisms. Zinc is required in the active site of the enzyme carboxypeptidase where it most likely functions in which of the following ways?

Accepted Answer

A)   as a noncompetitive inhibitor of the enzyme
B)   as an allosteric activator of the enzyme
C)   as a cofactor necessary for enzyme activity
D)   as a coenzyme derived from a vitaminE) A) and D)
F) All of the above

Question 8

Students conducting research observe the rate of an enzyme-catalyzed reaction under various conditions with a fixed amount of enzyme in each sample. When will increasing the substrate concentration likely result in the greatest increase in the reaction rate?

Accepted Answer

A)   when a cofactor is required in the reaction
B)   when an allosteric inhibitor is present in the reaction
C)   when a noncompetitive inhibitor is present in the reaction
D)   when a competitive inhibitor is present in the reactionE) A) and B)
F) B) and C)

Question 9

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions?

Accepted Answer

A)   The enzyme contains both α-helix and β-pleated sheet regions.
B)   The enzyme is subject to both competitive inhibition and allosteric regulation.
C)   The enzyme is composed of at least two identical subunits.
D)   The enzyme has two distinct active sites.E) A) and B)
F) A) and C)

Question 10

Which of the following statements best summarizes a consequence of the second law of thermodynamics?

Accepted Answer

A)   If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
B)   If the entropy of a system decreases, there must be a corresponding decrease in the entropy of the universe.
C)   If entropy of a system decreases, there must be a corresponding increase in the entropy of the universe.
D)   Each chemical reaction in an organism must decrease the total entropy of the universe.E) None of the above
F) B) and D)

Question 11

In addition to activating or inhibiting enzymes through allosteric regulation, which of these mechanisms do cells also use to control enzymatic activity?

Accepted Answer

A)   localization of enzymes into specific organelles or membranes
B)   secretion of enzymes out of the cell
C)   assembly of enzymes into large aggregates
D)   altering internal pHE) A) and B)
F) None of the above

Question 12

The 3-D structure of an enzyme composed of a single polypeptide chain includes a large substrate-binding domain. It also has a separate binding site for a regulatory molecule. Based on these structural observations the enzyme is most likely regulated by which of the following mechanism?

Accepted Answer

A)   noncompetitive inhibition
B)   competitive activation
C)   competitive inhibition
D)   cooperativityE) B) and C)
F) A) and D)

Question 13

An enzyme is composed of four identical subunits. Binding of substrate to one subunit stimulates more rapid binding of substrate to each of the other three subunits. This enzyme is most likely regulated by which of the following mechanisms?

Accepted Answer

A)   noncompetitive inhibition
B)   competitive activation
C)   competitive inhibition
D)   cooperativityE) A) and B)
F) A) and C)

Question 14

Use the following information to answer the question below.  The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the lower-case letters represents the activation energy required for the enzyme-catalyzed reaction in the figure?

Accepted Answer

A)   a
B)   b
C)   c
D)   dE) A) and B)
F) None of the above

Question 15

Use the following information to answer the question below.  The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the lower-case letters in the figure represents a free energy change that would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?

Accepted Answer

A)   a
B)   b
C)   c
D)   dE) B) and C)
F) None of the above

Question 16

A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme ________.

Accepted Answer

A)   folds to form secondary and tertiary structures
B)   interacts with water
C)   binds substrate
D)   is denatured by low pHE) B) and C)
F) A) and D)

Question 17

Which of the following examples describes a type of potential rather than kinetic energy?

Accepted Answer

A)   water rushing out of Hoover Dam
B)   flashes of light emitted by a firefly
C)   a sucrose molecule
D)   heat released by a campfireE) C) and D)
F) None of the above

Question 18

Which of the following molecules is most similar in structure to ATP?

Accepted Answer

A)   a pentose sugar
B)   a DNA nucleotide
C)   an RNA nucleotide
D)   an amino acid with three phosphate groups attachedE) All of the above
F) B) and D)

Question 19

Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do?

Accepted Answer

A)   Hydrolysis reactions increase G, or Gibbs free energy of the system.
B)   Hydrolysis reactions are endergonic and increase entropy of the system.
C)   Hydrolysis reactions are exergonic and decrease entropy of the system.
D)   Hydrolysis reactions are exergonic and increase entropy of the system.E) A) and B)
F) A) and C)

Question 20

The figure displays the relationship between initial rate of product formation and reactant concentration in an enzyme-catalyzed reaction with a fixed amount of enzyme. Which of the following statements best explains the shape of the rate curve at high reactant concentration?

Accepted Answer

A)   Feedback inhibition by product occurs at high reactant concentrations.
B)   Most enzyme molecules are occupied by substrate at high reactant concentrations.
C)   The reaction nears equilibrium at high reactant concentrations.
D)   The rate of the reverse reaction increases at high reactant concentrations.E) C) and D)
F) A) and C)

Exam 6: Energy and Life

Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones?

Correct Answer
verified

Which of the following molecules is most similar in structure to ATP?

Correct Answer
verified

Zinc is an essential trace element for most organisms. Zinc is required in the active site of the enzyme carboxypeptidase where it most likely functions in which of the following ways?

Correct Answer
verified

Which of the following statements best describes metabolism in its entirety in all organisms?

Correct Answer
verified

Students conducting research observe the rate of an enzyme-catalyzed reaction under various conditions with a fixed amount of enzyme in each sample. When will increasing the substrate concentration likely result in the greatest increase in the reaction rate?

Correct Answer
verified

In addition to activating or inhibiting enzymes through allosteric regulation, which of these mechanisms do cells also use to control enzymatic activity?

Correct Answer
verified

Penicillin is an antibiotic that kills bacteria by binding to the active site of an enzyme involved in synthesis of the bacterial cell wall. Which of the following phenomena best describes the mechanism of action of penicillin?

Correct Answer
verified

A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme ________.

Correct Answer
verified

An enzyme is composed of four identical subunits. Binding of substrate to one subunit stimulates more rapid binding of substrate to each of the other three subunits. This enzyme is most likely regulated by which of the following mechanisms?

Correct Answer
verified

The figure displays the relationship between initial rate of product formation and reactant concentration in an enzyme-catalyzed reaction with a fixed amount of enzyme. Which of the following statements best explains the shape of the rate curve at high reactant concentration?

Correct Answer
verified

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to ________.

Correct Answer
verified

Correct Answer
verified

Which of the following examples describes a type of potential rather than kinetic energy?

Correct Answer
verified

Which of the following statements best summarizes a consequence of the second law of thermodynamics?

Correct Answer
verified

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions?

Correct Answer
verified

The 3-D structure of an enzyme composed of a single polypeptide chain includes a large substrate-binding domain. It also has a separate binding site for a regulatory molecule. Based on these structural observations the enzyme is most likely regulated by which of the following mechanism?

Correct Answer
verified

When ATP is hydrolyzed to activate a target protein, what is often the fate of the inorganic phosphate that is released?

Correct Answer
verified

Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do?

Correct Answer
verified

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

Correct Answer
verified

Use the following information to answer the question below. The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the lower-case letters represents the activation energy required for the enzyme-catalyzed reaction in the figure?

Correct Answer
verified

Exam 6: Energy and Life

Which of the following terms most precisely identifies the cellular process of breaking down large molecules into smaller ones?

Correct AnswerverifiedShow Answer

Which of the following molecules is most similar in structure to ATP?

Correct AnswerverifiedShow Answer

Zinc is an essential trace element for most organisms. Zinc is required in the active site of the enzyme carboxypeptidase where it most likely functions in which of the following ways?

Correct AnswerverifiedShow Answer

Which of the following statements best describes metabolism in its entirety in all organisms?

Correct AnswerverifiedShow Answer

Students conducting research observe the rate of an enzyme-catalyzed reaction under various conditions with a fixed amount of enzyme in each sample. When will increasing the substrate concentration likely result in the greatest increase in the reaction rate?

Correct AnswerverifiedShow Answer

In addition to activating or inhibiting enzymes through allosteric regulation, which of these mechanisms do cells also use to control enzymatic activity?

Correct AnswerverifiedShow Answer

Penicillin is an antibiotic that kills bacteria by binding to the active site of an enzyme involved in synthesis of the bacterial cell wall. Which of the following phenomena best describes the mechanism of action of penicillin?

Correct AnswerverifiedShow Answer

A clasping handshake may be used as an analogy for an enzyme-catalyzed reaction because it represents the specific manner in which an enzyme ________.

Correct AnswerverifiedShow Answer

An enzyme is composed of four identical subunits. Binding of substrate to one subunit stimulates more rapid binding of substrate to each of the other three subunits. This enzyme is most likely regulated by which of the following mechanisms?

Correct AnswerverifiedShow Answer

The figure displays the relationship between initial rate of product formation and reactant concentration in an enzyme-catalyzed reaction with a fixed amount of enzyme. Which of the following statements best explains the shape of the rate curve at high reactant concentration?

Correct AnswerverifiedShow Answer

If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to ________.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Which of the following examples describes a type of potential rather than kinetic energy?

Correct AnswerverifiedShow Answer

Which of the following statements best summarizes a consequence of the second law of thermodynamics?

Correct AnswerverifiedShow Answer

Which of the following characteristics is most likely to be associated with an enzyme that catalyzes two different chemical reactions?

Correct AnswerverifiedShow Answer

The 3-D structure of an enzyme composed of a single polypeptide chain includes a large substrate-binding domain. It also has a separate binding site for a regulatory molecule. Based on these structural observations the enzyme is most likely regulated by which of the following mechanism?

Correct AnswerverifiedShow Answer

When ATP is hydrolyzed to activate a target protein, what is often the fate of the inorganic phosphate that is released?

Correct AnswerverifiedShow Answer

Which of the following statements best describes why hydrolysis reactions occur more readily in solution than dehydration reactions do?

Correct AnswerverifiedShow Answer

How does a noncompetitive inhibitor decrease the rate of an enzyme-catalyzed reaction?

Correct AnswerverifiedShow Answer

Use the following information to answer the question below. The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the lower-case letters represents the activation energy required for the enzyme-catalyzed reaction in the figure?

Correct AnswerverifiedShow Answer

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