Question 1

Explain how substrate concentration affects the rate of an enzyme-mediated reaction.

Accepted Answer

Increasing substrate concentration will result in an increased rate of reaction until all available active sites are occupied. At that point, no amount of substrate increase will increase the rate of reaction (see Figure 8.13).

Question 2

A readily reversible reaction, in which reactants and products have almost the same free energies, is indicated by a

Accepted Answer

A)  slightly negative $\Delta$G. 
B)  change in free energy. 
C)  negative $\Delta$G. 
D)  $\Delta$G near zero. 
E)  large positive $\Delta$G. 
A)  slightly negative $\Delta$G. 
B)  change in free energy. 
C)  negative $\Delta$G. 
D)  $\Delta$G near zero. 
E)  large positive $\Delta$G. D

Question 3

You are studying a new species never before studied. It lives in acidic pools in volcanic craters where temperatures often reach 100°C and normally stay above 90°C. You determine that it has a surface enzyme that catalyzes a reaction leading to its protective coating, and you decide to study this enzyme in the laboratory. Under what conditions would you most likely find optimal activity of this enzyme?

Accepted Answer

A)  0°C 
B)  37°C 
C)  55°C 
D)  95°C 
E)  105°C 
A)  0°C 
B)  37°C 
C)  55°C 
D)  95°C 
E)  105°C D

Question 4

In the pathway A + B $\to$  C + D, enzyme X facilitates the reaction. If compound D inhibits enzyme X, you would conclude that

Accepted Answer

A)  enzyme X is an allosteric inhibitor of the above reaction. 
B)  compound D is an allosteric stimulator of the above reaction. 
C)  compound D is a competitive inhibitor of the above reaction. 
D)  enzyme X is subject to feedback stimulation. 
E)  compound D is a coenzyme in the above reaction. 
A)  enzyme X is an allosteric inhibitor of the above reaction. 
B)  compound D is an allosteric stimulator of the above reaction. 
C)  compound D is a competitive inhibitor of the above reaction. 
D)  enzyme X is subject to feedback stimulation. 
E)  compound D is a coenzyme in the above reaction.

Question 5

During photosynthesis, plants use light energy to synthesize glucose from carbon dioxide. However, plants do not use up energy during photosynthesis; they merely convert it from light energy to chemical energy. This process is an illustration of

Accepted Answer

A)  increasing entropy. 
B)  chemical equilibrium. 
C)  the first law of thermodynamics. 
D)  the second law of thermodynamics. 
E)  a spontaneous reaction. 
A)  increasing entropy. 
B)  chemical equilibrium. 
C)  the first law of thermodynamics. 
D)  the second law of thermodynamics. 
E)  a spontaneous reaction.

Question 6

Which of the following statements about the exergonic hydrolysis of maltose to glucose is true?

Accepted Answer

A)  The reaction requires the input of free energy. 
B)  The free energy of glucose is larger than the free energy of maltose. 
C)  The reaction is not spontaneous. 
D)  The reaction releases free energy. 
E)  At equilibrium, the concentration of maltose is higher than the concentration of glucose. 
A)  The reaction requires the input of free energy. 
B)  The free energy of glucose is larger than the free energy of maltose. 
C)  The reaction is not spontaneous. 
D)  The reaction releases free energy. 
E)  At equilibrium, the concentration of maltose is higher than the concentration of glucose.

Question 7

How does the second law of thermodynamics apply to organisms?

Accepted Answer

A)  As energy transformations occur, free energy increases and unusable energy decreases. 
B)  To maintain order, life requires a constant input of energy. 
C)  The potential energy of ATP is converted to kinetic energy such as muscle contractions. 
D)  Reactions occur only with an input of energy. 
E)  It does not apply to organisms; the complexity of organisms contradicts the second law. 
A)  As energy transformations occur, free energy increases and unusable energy decreases. 
B)  To maintain order, life requires a constant input of energy. 
C)  The potential energy of ATP is converted to kinetic energy such as muscle contractions. 
D)  Reactions occur only with an input of energy. 
E)  It does not apply to organisms; the complexity of organisms contradicts the second law.

Question 8

Enzymes

Accepted Answer

A)  may be subject to feedback inhibition. 
B)  change the value of $\Delta$G for a reaction. 
C)  always require cofactors. 
D)  have no effect on the activation energy barrier of a reaction. 
E)  are permanently changed by the reactions they facilitate. 
A)  may be subject to feedback inhibition. 
B)  change the value of $\Delta$G for a reaction. 
C)  always require cofactors. 
D)  have no effect on the activation energy barrier of a reaction. 
E)  are permanently changed by the reactions they facilitate.

Question 9

An allosteric inhibitor

Accepted Answer

A)  decreases the concentration of an inactive enzyme. 
B)  changes the shape of an enzyme. 
C)  increases the concentration of a product. 
D)  changes the shape of a substrate. 
E)  increases the concentration of an enzyme-substrate complex. 
A)  decreases the concentration of an inactive enzyme. 
B)  changes the shape of an enzyme. 
C)  increases the concentration of a product. 
D)  changes the shape of a substrate. 
E)  increases the concentration of an enzyme-substrate complex.

Question 10

A change in enzyme shape caused by substrate binding is called _______.

Accepted Answer

The answer of A change in enzyme shape caused by...

Question 11

Which statement about thermodynamics is true?

Accepted Answer

A)  Free energy is used up in an exergonic reaction. 
B)  Free energy cannot be used to do work. 
C)  The total amount of energy can change after a chemical transformation. 
D)  Free energy can be kinetic but not potential energy. 
E)  Entropy has a tendency to increase. 
A)  Free energy is used up in an exergonic reaction. 
B)  Free energy cannot be used to do work. 
C)  The total amount of energy can change after a chemical transformation. 
D)  Free energy can be kinetic but not potential energy. 
E)  Entropy has a tendency to increase.

Question 12

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\to$ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Accepted Answer

A)  transition state. 
B)  activation groove. 
C)  catalyst. 
D)  enzyme-substrate complex. 
E)  energy barrier. 
A)  transition state. 
B)  activation groove. 
C)  catalyst. 
D)  enzyme-substrate complex. 
E)  energy barrier.

Question 13

Which of the following represents an enzyme-catalyzed reaction? (E = enzyme, P = product, S = substrate)

Accepted Answer

A)  E + P $\to$ E + S 
B)  E + S $\to$  E + P 
C)  E + S $\to$  P 
D)  E + S $\to$  E 
E)  P + S $\to$  E 
A)  E + P $\to$ E + S 
B)  E + S $\to$  E + P 
C)  E + S $\to$  P 
D)  E + S $\to$  E 
E)  P + S $\to$  E

Question 14

Enzymes are biological _______.

Accepted Answer

The answer of Enzymes are biological _______....

Question 15

A change in free energy is related to a change in

Accepted Answer

A)  temperature. 
B)  entropy. 
C)  pressure. 
D)  Both a and b 
E)  All of the above 
A)  temperature. 
B)  entropy. 
C)  pressure. 
D)  Both a and b 
E)  All of the above

Question 16

When ADP gains a phosphate to form ATP,

Accepted Answer

A)  free energy is released by the loss of a phosphate. 
B)  energy is consumed. 
C)  the reaction ends. 
D)  chemical energy is converted to light energy. 
E)  ribose loses an oxygen to become deoxyribose. 
A)  free energy is released by the loss of a phosphate. 
B)  energy is consumed. 
C)  the reaction ends. 
D)  chemical energy is converted to light energy. 
E)  ribose loses an oxygen to become deoxyribose.

Question 17

The enzyme phosphoglucoisomerase catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate. The region on phosphoglucoisomerase where glucose 6-phosphate binds is called the _______.

Accepted Answer

The answer of The enzyme phosphoglucoisomerase catalyzes the conversion of...

Question 18

Why is the statement, "ATP produces energy for life," wrong?

Accepted Answer

A)  It requires energy to make ATP. 
B)  It is a violation of the second law of thermodynamics. 
C)  It is a violation of the first law of kinetics. 
D)  It is a violation of the first law of thermodynamics. 
E)  Life produces ATP. 
A)  It requires energy to make ATP. 
B)  It is a violation of the second law of thermodynamics. 
C)  It is a violation of the first law of kinetics. 
D)  It is a violation of the first law of thermodynamics. 
E)  Life produces ATP.

Question 19

In some cases, a substrate-enzyme complex is stabilized by

Accepted Answer

A)  hydrogen bonds. 
B)  covalent bonds. 
C)  ionic attractions. 
D)  hydrophobic interactions. 
E)  All of the above 
A)  hydrogen bonds. 
B)  covalent bonds. 
C)  ionic attractions. 
D)  hydrophobic interactions. 
E)  All of the above

Question 20

Which of the following are characteristics of enzymes?

Accepted Answer

A)  They are consumed by the enzyme-mediated reaction. 
B)  They are not altered by the enzyme-mediated reaction. 
C)  They raise activation energy. 
D)  They can be composed of RNA or proteins. 
E)  They are only rarely regulated. 
A)  They are consumed by the enzyme-mediated reaction. 
B)  They are not altered by the enzyme-mediated reaction. 
C)  They raise activation energy. 
D)  They can be composed of RNA or proteins. 
E)  They are only rarely regulated.

Exam 8: Energy, Enzymes, and Metabolism

Explain how substrate concentration affects the rate of an enzyme-mediated reaction.

A readily reversible reaction, in which reactants and products have almost the same free energies, is indicated by a

In the pathway A + B →\to→ C + D, enzyme X facilitates the reaction. If compound D inhibits enzyme X, you would conclude that

During photosynthesis, plants use light energy to synthesize glucose from carbon dioxide. However, plants do not use up energy during photosynthesis; they merely convert it from light energy to chemical energy. This process is an illustration of

Which of the following statements about the exergonic hydrolysis of maltose to glucose is true?

How does the second law of thermodynamics apply to organisms?

Enzymes

An allosteric inhibitor

A change in enzyme shape caused by substrate binding is called _______.

Which statement about thermodynamics is true?

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate →\to→ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)

Which of the following represents an enzyme-catalyzed reaction? (E = enzyme, P = product, S = substrate)

Enzymes are biological _______.

A change in free energy is related to a change in

When ADP gains a phosphate to form ATP,

The enzyme phosphoglucoisomerase catalyzes the conversion of glucose 6-phosphate to fructose 6-phosphate. The region on phosphoglucoisomerase where glucose 6-phosphate binds is called the _______.

Why is the statement, "ATP produces energy for life," wrong?

In some cases, a substrate-enzyme complex is stabilized by

Which of the following are characteristics of enzymes?

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 Signaling and Communication

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

Recombinent Dna and Biotechnology

Differential Gene Expression in Development

Development and Evolutionary Change

Evidence and Mechanisms of Evolution

Reconstructing and Using Phylogenies

Species and Their Formation

Evolution of Genes and Genomes

The History of Life on Earth

Bacteria and Archaea: the Prokaryotic Domains

The Origin and Diversification of Eukaryotes

Plants Without Seeds: From Water to Land

The Evolution of Seed Plants

Fungi: Recyclers, Pathogens, Parasites, and Plant Partners

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 and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Function

Musculoskeletal Systems

Gas Exchange in Animals

Circulatory Systems

Nutrition, Digestion, and Absorption

Salt and Water Balance and Nitrogen

Animal Behavior

Ecology and the Distribution of Life

Population Ecology

Species Interaction and Coevolution

Community Ecology

Ecosystems and Global Ecology

Conservation Biology

Filters

In the pathway A + B $\to$ C + D, enzyme X facilitates the reaction. If compound D inhibits enzyme X, you would conclude that

The enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the reaction glyceraldehyde 3-phosphate $\to$ 1,3-diphosphoglycerate. The binding of the glyceraldehyde 3-phosphate to the enzyme creates a(n)