Question 1

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. 
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.

Question 2

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)  d 
A)  a 
B)  b 
C)  c 
D)  d

Question 3

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 vitamin 
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 vitamin

Question 4

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. 
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.

Question 5

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)  cooperativity 
A)  noncompetitive inhibition 
B)  competitive activation 
C)  competitive inhibition 
D)  cooperativity

Question 6

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 reaction 
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 reaction

Question 7

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 campfire 
A)  water rushing out of Hoover Dam 
B)  flashes of light emitted by a firefly 
C)  a sucrose molecule 
D)  heat released by a campfire

Question 8

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. 
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.

Question 9

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

Question 10

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 pH 
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 pH

Question 11

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. 
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.

Question 12

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. 
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.

Question 13

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 reaction 
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 reaction

Question 14

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 inhibition 
A)  noncompetitive inhibition 
B)  feedback inhibition 
C)  allosteric regulation 
D)  competitive inhibition

Question 15

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 attached 
A)  a pentose sugar 
B)  a DNA nucleotide 
C)  an RNA nucleotide 
D)  an amino acid with three phosphate groups attached

Question 16

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)  d 
A)  a 
B)  b 
C)  c 
D)  d

Question 17

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. 
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.

Question 18

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 inhibitor 
A)  add more of the enzyme 
B)  heat the solution to 90°C 
C)  add more substrate 
D)  add a noncompetitive inhibitor

Question 19

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)  cooperativity 
A)  noncompetitive inhibition 
B)  competitive activation 
C)  competitive inhibition 
D)  cooperativity

Question 20

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)  dehydration 
A)  catabolism (catabolic pathways) 
B)  metabolism 
C)  anabolism (anabolic pathways) 
D)  dehydration

Exam 6: Energy and Life

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

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?

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?

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?

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?

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

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

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

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

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

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

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

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?

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?

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

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

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

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?

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

Biology and Its Themes

Atoms and Molecules

The Chemistry of Water

Carbon: the Basis of Molecular Diversity

Biological Macromolecules and Lipids

Cell Structure and Function

Cell Membranes

Cellular Signaling

Cell Respiration

Photosynthetic Processes

Mitosis

Sexual Life Cycles and Meiosis

Mendelian Genetics

Linkage and Chromosomes

Nucleic Acids and Inheritance

Expression of Genes

Control of Gene Expression

Dna Technology

The Evolution of Genomes

How Evolution Works

Phylogenetic Reconstruction

Microevolution

Species and Speciation

Macroevolution

Introduction to Viruses

Prokaryotes

The Origin and Evolution of Eukaryotes

Nonvascular and Seedless Vascular Plants

Seed Plants

Introduction to Fungi

An Introduction to Animal Diversity

Invertebrates

Vertebrates

Plant Structure and Growth

Transport in Vascular Plants

Plant Nutrition

Reproduction of Flowering Plants

Plant Signals and Behavior

The Animal Body

Chemical Signals in Animals

Animal Digestive Systems

Animal Transport Systems

Animal Excretory Systems

Animal Reproductive Systems

Development in Animals

Animal Defenses Against Infection

Electrical Signals in Animals

Neural Regulation in Animals

Sensation and Movement in Animals

An Overview of Ecology

Behavioral Ecology

Populations and Life History Traits

Biodiversity and Communities

Energy Flow and Chemical Cycling in Ecosystems

Conservation and Global Ecology

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