Question 1

The binding of a substrate to an enzyme

Accepted Answer

A)  is always covalent. 
B)  is irreversible. 
C)  is nonspecific. 
D)  may involve hydrogen bonds and van der Waals interactions. 
E)  does not induce shape changes in the enzyme. 
A)  is always covalent. 
B)  is irreversible. 
C)  is nonspecific. 
D)  may involve hydrogen bonds and van der Waals interactions. 
E)  does not induce shape changes in the enzyme.

Question 2

The synthesis of complex molecules is _______, whereas their degradation is _______.Synthesis occurs with _______ in entropy.

Accepted Answer

A)  endergonic; exergonic; an increase 
B)  endergonic; exergonic; a decrease 
C)  exergonic; endergonic; no change 
D)  exergonic; endergonic; an increase 
E)  endergonic; exergonic; no change 
A)  endergonic; exergonic; an increase 
B)  endergonic; exergonic; a decrease 
C)  exergonic; endergonic; no change 
D)  exergonic; endergonic; an increase 
E)  endergonic; exergonic; no change

Question 3

An enzyme

Accepted Answer

A)  decreases the F1F1F1S1F1F1F10G of a reaction. 
B)  shifts the equilibrium point of a reaction. 
C)  creates an energy barrier for a reaction. 
D)  is a catalyst. 
E)  has an activity that is not affected by its three-dimensional structure. 
A)  decreases the F1F1F1S1F1F1F10G of a reaction. 
B)  shifts the equilibrium point of a reaction. 
C)  creates an energy barrier for a reaction. 
D)  is a catalyst. 
E)  has an activity that is not affected by its three-dimensional structure.

Question 4

Phosphofructoisomerase is classified as an isomerase enzyme, and pyruvate dehydrogenase is classified as an oxidoreductase enzyme.Which feature do both enzymes share?

Accepted Answer

A)  They share a similar concentration of substrate corresponding to saturating levels for 1 nanomole of enzyme. 
B)  They share the same shape of the curve when enzyme activity is plotted against substrate concentration. 
C)  They share the same position of the peak on a graph of enzyme activity versus pH. 
D)  They share the same temperature at which the enzyme begins to denature as heat is gradually added. 
E)  They share the same dissociation constant for substrate binding. 
A)  They share a similar concentration of substrate corresponding to saturating levels for 1 nanomole of enzyme. 
B)  They share the same shape of the curve when enzyme activity is plotted against substrate concentration. 
C)  They share the same position of the peak on a graph of enzyme activity versus pH. 
D)  They share the same temperature at which the enzyme begins to denature as heat is gradually added. 
E)  They share the same dissociation constant for substrate binding.

Question 5

The presence of a catalyst affects the

Accepted Answer

A)  position of equilibrium of the reaction. 
B)  overall energy change, or F1F1F1S1F1F1F10G. 
C)  energy of the reactants. 
D)  energy of the products. 
E)  free energy of the transition state. 
A)  position of equilibrium of the reaction. 
B)  overall energy change, or F1F1F1S1F1F1F10G. 
C)  energy of the reactants. 
D)  energy of the products. 
E)  free energy of the transition state.

Question 6

Refer to the table below.   A student constructed the table to summarize characteristics that distinguish anabolic reactions from catabolic reactions.Which statement best evaluates the accuracy of the student's work?

Accepted Answer

A)  The table is correct as shown. 
B)  The entries concerning molecular changes and role in metabolism are incorrect and should be reversed. 
C)  The entries concerning direction of energy flow are incorrect and should be reversed. 
D)  The entries concerning changes in potential energy are incorrect and should be reversed. 
E)  The examples used are incorrect and should be reversed. 
A)  The table is correct as shown. 
B)  The entries concerning molecular changes and role in metabolism are incorrect and should be reversed. 
C)  The entries concerning direction of energy flow are incorrect and should be reversed. 
D)  The entries concerning changes in potential energy are incorrect and should be reversed. 
E)  The examples used are incorrect and should be reversed.

Question 7

A key difference between coenzymes and inorganic cofactors is that

Accepted Answer

A)  inorganic cofactors are not covalently bound to the enzyme, whereas coenzymes are. 
B)  coenzymes are carbon-containing molecules, whereas inorganic cofactors are usually ions. 
C)  coenzymes are usually ions, whereas inorganic cofactors are typically carbon-containing molecules. 
D)  inorganic cofactors dissociate from an enzyme after a reaction, whereas coenzymes remain permanently bound. 
E)  coenzymes have intrinsic catalytic activity, whereas inorganic cofactors do not. 
A)  inorganic cofactors are not covalently bound to the enzyme, whereas coenzymes are. 
B)  coenzymes are carbon-containing molecules, whereas inorganic cofactors are usually ions. 
C)  coenzymes are usually ions, whereas inorganic cofactors are typically carbon-containing molecules. 
D)  inorganic cofactors dissociate from an enzyme after a reaction, whereas coenzymes remain permanently bound. 
E)  coenzymes have intrinsic catalytic activity, whereas inorganic cofactors do not.

Question 8

Which graph shows changes in the rate of an enzyme-catalyzed reaction as substrate concentration is varied?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 9

The statement "enzymes are highly specific" means that specific

Accepted Answer

A)  enzymes are found in specific cells. 
B)  reactions involving specific substrates are catalyzed by specific enzymes. 
C)  enzymes require specific concentrations of substrates. 
D)  reactions with specific activation energies are catalyzed by specific enzymes. 
E)  concentrations of substrates work with specific enzymes. 
A)  enzymes are found in specific cells. 
B)  reactions involving specific substrates are catalyzed by specific enzymes. 
C)  enzymes require specific concentrations of substrates. 
D)  reactions with specific activation energies are catalyzed by specific enzymes. 
E)  concentrations of substrates work with specific enzymes.

Question 10

Which statement about ATP is true?

Accepted Answer

A)  The hydrolysis of ATP is endergonic. 
B)  ATP consists of adenine bonded to deoxyribose. 
C)  ATP releases a large amount of light energy when hydrolyzed. 
D)  An active cell requires about 100 molecules of ATP per second. 
E)  On average, ATP is consumed within 1 second of its formation. 
A)  The hydrolysis of ATP is endergonic. 
B)  ATP consists of adenine bonded to deoxyribose. 
C)  ATP releases a large amount of light energy when hydrolyzed. 
D)  An active cell requires about 100 molecules of ATP per second. 
E)  On average, ATP is consumed within 1 second of its formation.

Question 11

Which statement regarding enzyme-substrate (ES) complexes is true?

Accepted Answer

A)  The formation of an ES complex helps to lower the F1F1F1S1F1F1F10G of the reaction, favoring product formation. 
B)  The formation of an ES complex helps to lower the F1F1F1S1F1F1F10H of the reaction, favoring product formation. 
C)  The formation of an ES complex helps to achieve the transition state, favoring product formation. 
D)  The formation of an ES complex helps to convert the chemical reaction from exergonic to endergonic. 
E)  The formation of an ES complex helps to convert the chemical reaction from endergonic to exergonic. 
A)  The formation of an ES complex helps to lower the F1F1F1S1F1F1F10G of the reaction, favoring product formation. 
B)  The formation of an ES complex helps to lower the F1F1F1S1F1F1F10H of the reaction, favoring product formation. 
C)  The formation of an ES complex helps to achieve the transition state, favoring product formation. 
D)  The formation of an ES complex helps to convert the chemical reaction from exergonic to endergonic. 
E)  The formation of an ES complex helps to convert the chemical reaction from endergonic to exergonic.

Question 12

The enzyme sucrase increases the rate at which sucrose is broken down into glucose and fructose.Sucrase works by

Accepted Answer

A)  increasing the amount of free energy of the reaction. 
B)  lowering the activation energy of the reaction. 
C)  decreasing the equilibrium constant of the reaction. 
D)  supplying energy to speed up the reaction. 
E)  changing the shape of the active site. 
A)  increasing the amount of free energy of the reaction. 
B)  lowering the activation energy of the reaction. 
C)  decreasing the equilibrium constant of the reaction. 
D)  supplying energy to speed up the reaction. 
E)  changing the shape of the active site.

Question 13

Which statement disagrees with the second law of thermodynamics?

Accepted Answer

A)  The disorder of a system and its surroundings decreases overall with time. 
B)  Chemical energy may be converted to light energy. 
C)  Only a portion of the total energy of a system is available to do work. 
D)  Potential energy may be used to do work. 
E)  During energy conversion, some energy can be lost as heat. 
A)  The disorder of a system and its surroundings decreases overall with time. 
B)  Chemical energy may be converted to light energy. 
C)  Only a portion of the total energy of a system is available to do work. 
D)  Potential energy may be used to do work. 
E)  During energy conversion, some energy can be lost as heat.

Question 14

At a chemical equilibrium of 14:1 reactants to products, what would be the final concentration of the reactants if the input concentration were 3.0 M?

Accepted Answer

A)  0.1 M 
B)  0.2 M 
C)  1.5 M 
D)  2.8 M 
E)  3.0 M 
A)  0.1 M 
B)  0.2 M 
C)  1.5 M 
D)  2.8 M 
E)  3.0 M

Question 15

During muscle contractions, chemical energy is converted to kinetic energy of movement and also to thermal energy, which dissipates into the surroundings as heat.With respect to the second law of thermodynamics, which event occurs in this example?

Accepted Answer

A)  Disorder decreases. 
B)  Entropy increases. 
C)  Chemical equilibrium is achieved. 
D)  Total free energy increases. 
E)  Enthalpy increases. 
A)  Disorder decreases. 
B)  Entropy increases. 
C)  Chemical equilibrium is achieved. 
D)  Total free energy increases. 
E)  Enthalpy increases.

Question 16

When potatoes are peeled, the enzyme polyphenol oxidase causes discoloration by catalyzing the oxidation of certain molecules, using O2 as a substrate.Explain the following observations:
a. If potatoes are peeled under water and kept there, browning is reduced.
b. Potatoes that have been boiled at 100F1F1F1S1F1F1F10C and then sliced do not turn brown.
c. If lemon juice (pH 3) is applied to newly peeled potatoes, they do not brown.

Accepted Answer

(a) The presence of water may prevent O₂

Question 17

If the enzyme phosphohexoisomerase is added to a 0.3 M solution of fructose 6-phosphate and the reaction is allowed to proceed to equilibrium, the final concentrations are 0.2 M glucose 6-phosphate and 0.1 M fructose 6-phosphate.What would be the final concentration of glucose 6-phosphate if the initial concentration of fructose 6-phosphate were changed to 3 M?

Accepted Answer

A)  2 M 
B)  3 M 
C)  1 M 
D)  0.5 M 
E)  0.2 M 
A)  2 M 
B)  3 M 
C)  1 M 
D)  0.5 M 
E)  0.2 M

Question 18

Mechanisms used by enzymes to catalyze reactions are similar in that they all

Accepted Answer

A)  involve transient chemical change in the enzyme. 
B)  involve permanent chemical change in the enzyme. 
C)  lead to stabilization of the transition state of the substrate. 
D)  require the involvement of cofactors or coenzymes. 
E)  work individually in any one enzyme and not in conjunction with one another. 
A)  involve transient chemical change in the enzyme. 
B)  involve permanent chemical change in the enzyme. 
C)  lead to stabilization of the transition state of the substrate. 
D)  require the involvement of cofactors or coenzymes. 
E)  work individually in any one enzyme and not in conjunction with one another.

Question 19

Refer to the reaction below.   The enzyme catalyzing this reaction would be classified along with other enzymes of the same type as a(n) _______.

Accepted Answer

The answer of Refer to the reaction below.  ...

Question 20

Which action could indicate whether a given reaction is endergonic? Assume that no other small molecules are present in the reaction solution.

Accepted Answer

A)  Add ATP and see if the reaction creates more product. 
B)  Add ADP and see if the reaction creates phosphate ions. 
C)  Add adenine and see if the reaction makes reactants instead of product. 
D)  Add phosphate and see if the reaction creates ATP. 
E)  Add water and see if the reaction produces ADP. 
A)  Add ATP and see if the reaction creates more product. 
B)  Add ADP and see if the reaction creates phosphate ions. 
C)  Add adenine and see if the reaction makes reactants instead of product. 
D)  Add phosphate and see if the reaction creates ATP. 
E)  Add water and see if the reaction produces ADP.

Exam 8: Energy, Enzymes, and Metabolism

The binding of a substrate to an enzyme

The synthesis of complex molecules is _______, whereas their degradation is _______.Synthesis occurs with _______ in entropy.

An enzyme

Phosphofructoisomerase is classified as an isomerase enzyme, and pyruvate dehydrogenase is classified as an oxidoreductase enzyme.Which feature do both enzymes share?

The presence of a catalyst affects the

Refer to the table below. A student constructed the table to summarize characteristics that distinguish anabolic reactions from catabolic reactions.Which statement best evaluates the accuracy of the student's work?

A key difference between coenzymes and inorganic cofactors is that

Which graph shows changes in the rate of an enzyme-catalyzed reaction as substrate concentration is varied?

The statement "enzymes are highly specific" means that specific

Which statement about ATP is true?

Which statement regarding enzyme-substrate (ES) complexes is true?

The enzyme sucrase increases the rate at which sucrose is broken down into glucose and fructose.Sucrase works by

Which statement disagrees with the second law of thermodynamics?

At a chemical equilibrium of 14:1 reactants to products, what would be the final concentration of the reactants if the input concentration were 3.0 M?

During muscle contractions, chemical energy is converted to kinetic energy of movement and also to thermal energy, which dissipates into the surroundings as heat.With respect to the second law of thermodynamics, which event occurs in this example?

Mechanisms used by enzymes to catalyze reactions are similar in that they all

Refer to the reaction below. The enzyme catalyzing this reaction would be classified along with other enzymes of the same type as a(n) _______.

Which action could indicate whether a given reaction is endergonic? Assume that no other small molecules are present in the reaction solution.

Studying Life

Small Molecules and the Chemistry of Life

Proteins, Carbohydrates, and Lipids

Nucleic Acids and the Origin of Life

Cells: the Working Units of Life

Cell Membranes

Cell Communication and Multicellularity

Pathways That Harvest Chemical Energy

Photosynthesis: Energy From Sunlight

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

Dna and Its Role in Heredity

From Dna to Protein: Gene Expression

Gene Mutation and Molecular Medicine

Regulation of Gene Expression

Genomes

Recombinant Dna and Biotechnology

Mechanisms of Evolution

Reconstructing and Using Phylogenies

Speciation

Evolution of Genes and Genomes

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

Plants Without Seeds: From Water to Land

The Evolution of Seed Plants

The Evolution and Diversity of Fungi

Animal Origins and the Evolution of Body Plans

Protostome Animals

Deuterostome Animals

The Plant Body

Transport in Plants

Plant Nutrition

Regulation of Plant Growth

Reproduction in Flowering Plants

Plant Responses to Environmental Challenges

Physiology, Homeostasis, and Temperature Regulation

Animal Hormones

Immunology: Animal Defense Systems

Animal Reproduction

Animal Development

Neurons, Glia, and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Functions

Musculoskeletal Systems

Gas Exchange

Circulatory Systems

Nutrition, Digestion, and Absorption

Salt and Water Balance and Nitrogen Excretion

Animal Behavior

The Physical Environment and Biogeography of Life

Populations

Species Interactions

Communities

Ecosystems

A Changing Biosphere

Filters

The synthesis of complex molecules is ___, whereas their degradation is _.Synthesis occurs with _____ in entropy.