Question 1

Enzymes are highly sensitive to pH and temperature because

Accepted Answer

A)  changes in the environment raise their activation energy. 
B)  changes in temperature and pH readily break their hydrogen bonds. 
C)  of their three-dimensional structure and side chains. 
D)  at extreme temperatures and pH levels, coenzymes add chemical groups to the substrate. 
E)  extremes of temperature and pH level change the ionization rate. 
A)  changes in the environment raise their activation energy. 
B)  changes in temperature and pH readily break their hydrogen bonds. 
C)  of their three-dimensional structure and side chains. 
D)  at extreme temperatures and pH levels, coenzymes add chemical groups to the substrate. 
E)  extremes of temperature and pH level change the ionization rate.

Question 2

If $\Delta$G for a reaction is positive, the reaction

Accepted Answer

A)  is spontaneous. 
B)  could drive an energy-requiring process. 
C)  is endergonic. 
D)  would necessarily have a positive $\Delta$H. 
E)  would proceed quickly. 
A)  is spontaneous. 
B)  could drive an energy-requiring process. 
C)  is endergonic. 
D)  would necessarily have a positive $\Delta$H. 
E)  would proceed quickly.

Question 3

Metabolism is organized into pathways that are linked in which of the following ways?

Accepted Answer

A)  All cellular functions feed into a central pathway. 
B)  All steps in the pathway are catalyzed by the same enzyme. 
C)  The product of one step in the pathway functions as the substrate in the next step. 
D)  Products of the pathway accumulate and are secreted from the cell. 
E)  Different substrates are acted on by the same enzyme. 
A)  All cellular functions feed into a central pathway. 
B)  All steps in the pathway are catalyzed by the same enzyme. 
C)  The product of one step in the pathway functions as the substrate in the next step. 
D)  Products of the pathway accumulate and are secreted from the cell. 
E)  Different substrates are acted on by the same enzyme.

Question 4

The capacity for change is known as _______.

Accepted Answer

The answer of The capacity for change is known as...

Question 5

Which of the following statements about enzymes is true?

Accepted Answer

A)  Enzymes are proteins. 
B)  Enzymes have a specific amino acid sequence. 
C)  Enzymes are highly specific. 
D)  Enzymes lower the energy barrier. 
E)  All of the above 
A)  Enzymes are proteins. 
B)  Enzymes have a specific amino acid sequence. 
C)  Enzymes are highly specific. 
D)  Enzymes lower the energy barrier. 
E)  All of the above

Question 6

The sum total of all the chemical reactions in a living structure is called its

Accepted Answer

A)  energetics. 
B)  activity. 
C)  digestive power. 
D)  entropy. 
E)  metabolism. 
A)  energetics. 
B)  activity. 
C)  digestive power. 
D)  entropy. 
E)  metabolism.

Question 7

Which of the following statements is (are) inconsistent with the first and second laws of thermodynamics?

Accepted Answer

A)  Living organisms can produce energy. 
B)  Chemical energy may be converted to light energy. 
C)  The total energy of a system is available to do work. 
D)  Potential energy may be used to do work. 
E)  Both a and c 
A)  Living organisms can produce energy. 
B)  Chemical energy may be converted to light energy. 
C)  The total energy of a system is available to do work. 
D)  Potential energy may be used to do work. 
E)  Both a and c

Question 8

The rate of a chemical reaction in a cell is the measure of how

Accepted Answer

A)  often the reaction occurs. 
B)  quickly the reaction reaches equilibrium. 
C)  much energy must be added for the reaction to occur. 
D)  much activation energy is required for the reaction to occur. 
E)  easily the reaction is inhibited. 
A)  often the reaction occurs. 
B)  quickly the reaction reaches equilibrium. 
C)  much energy must be added for the reaction to occur. 
D)  much activation energy is required for the reaction to occur. 
E)  easily the reaction is inhibited.

Question 9

Environmental conditions that affect enzyme function include

Accepted Answer

A)  temperature. 
B)  pH. 
C)  CO2 concentration. 
D)  Both a and b 
E)  All of the above 
A)  temperature. 
B)  pH. 
C)  CO2 concentration. 
D)  Both a and b 
E)  All of the above

Question 10

In the presence of alcohol dehydrogenase, the rate of reduction of acetaldehyde to ethanol increases as the concentration of acetaldehyde is increased. Eventually, the rate of the reaction reaches a maximum, at which point further increases in the concentration of acetaldehyde have no effect. Why?

Accepted Answer

A)  All the alcohol dehydrogenase molecules are bound to acetaldehyde molecules. 
B)  At high concentrations of acetaldehyde, the activation energy of the reaction increases. 
C)  At high concentrations of acetaldehyde, the activation energy of the reaction decreases. 
D)  The enzyme is no longer specific for acetaldehyde. 
E)  At high concentrations of acetaldehyde, the change in free energy of the reaction decreases. 
A)  All the alcohol dehydrogenase molecules are bound to acetaldehyde molecules. 
B)  At high concentrations of acetaldehyde, the activation energy of the reaction increases. 
C)  At high concentrations of acetaldehyde, the activation energy of the reaction decreases. 
D)  The enzyme is no longer specific for acetaldehyde. 
E)  At high concentrations of acetaldehyde, the change in free energy of the reaction decreases.

Question 11

You are given an unlabeled enzyme and told to add a compound to the container that will irreversibly bind to the enzyme and increase its function. You ask for information about the enzyme, but your instructor simply hands you a list of possible compounds. Based on what you have learned about the enzyme partners below, which one is the best choice?

Accepted Answer

A)  Coenzyme A 
B)  Zinc (Zn2+) 
C)  Flavin 
D)  ATP 
E)  NAD 
A)  Coenzyme A 
B)  Zinc (Zn2+) 
C)  Flavin 
D)  ATP 
E)  NAD

Question 12

Many enzymes require ATP and ADP for a reaction to occur. They temporarily bind to and then release from the substrate to participate in other reactions. ATP and ADP are considered

Accepted Answer

A)  a side chain. 
B)  coenzymes. 
C)  a coupled reaction. 
D)  a prosthetic group. 
E)  cofactors. 
A)  a side chain. 
B)  coenzymes. 
C)  a coupled reaction. 
D)  a prosthetic group. 
E)  cofactors.

Question 13

Which of the following statements about allosteric regulators is true?

Accepted Answer

A)  The plot for allosteric regulators often has a sigmoid curve. 
B)  All enzymes are allosterically regulated. 
C)  Enzymes that are allosterically regulated are made of multiple polypeptide subunits. 
D)  Both the active site and the regulatory site are present on the same subunit. 
E)  Allosteric regulators bind to the active site, blocking enzyme function. 
A)  The plot for allosteric regulators often has a sigmoid curve. 
B)  All enzymes are allosterically regulated. 
C)  Enzymes that are allosterically regulated are made of multiple polypeptide subunits. 
D)  Both the active site and the regulatory site are present on the same subunit. 
E)  Allosteric regulators bind to the active site, blocking enzyme function.

Question 14

The second law of thermodynamics states that the _______, or disorder, of the universe is constantly increasing.

Accepted Answer

The answer of The second law of thermodynamics states that...

Question 15

Water held back by a dam represents what kind of energy?

Accepted Answer

A)  Hydroelectric 
B)  Irrigation 
C)  Potential 
D)  Kinetic 
E)  At times, all of the above 
A)  Hydroelectric 
B)  Irrigation 
C)  Potential 
D)  Kinetic 
E)  At times, all of the above

Question 16

A noncompetitive inhibitor inhibits binding of a substrate to an enzyme by

Accepted Answer

A)  binding to the substrate. 
B)  binding to the active site. 
C)  lowering the activation energy. 
D)  increasing the $\Delta$G of the reaction. 
E)  changing the shape of the active site. 
A)  binding to the substrate. 
B)  binding to the active site. 
C)  lowering the activation energy. 
D)  increasing the $\Delta$G of the reaction. 
E)  changing the shape of the active site.

Question 17

Lactose intolerance is due to the

Accepted Answer

A)  inability to hydrolyze polysaccharides. 
B)  body's ability to digest lactose but inability to absorb the resulting products. 
C)  gaseous side products produced in the small intestine. 
D)  inability to produce the enzyme lactase. 
E)  inability to oxidate luciferase. 
A)  inability to hydrolyze polysaccharides. 
B)  body's ability to digest lactose but inability to absorb the resulting products. 
C)  gaseous side products produced in the small intestine. 
D)  inability to produce the enzyme lactase. 
E)  inability to oxidate luciferase.

Question 18

Fireflies

Accepted Answer

A)  release a considerable amount of energy as heat. 
B)  light up to signal danger. 
C)  use ATP to begin luciferin oxidation. 
D)  are constantly converting light energy into chemical energy. 
E)  have a short life cycle due to rapid depletion of ATP. 
A)  release a considerable amount of energy as heat. 
B)  light up to signal danger. 
C)  use ATP to begin luciferin oxidation. 
D)  are constantly converting light energy into chemical energy. 
E)  have a short life cycle due to rapid depletion of ATP.

Question 19

An allosteric enzyme

Accepted Answer

A)  usually contains a single polypeptide chain. 
B)  may show a sigmoid dependence on substrate concentration. 
C)  is not subject to regulation of its activity. 
D)  often catalyzes a reaction near the end of a pathway. 
E)  is normally subject to irreversible inhibition. 
A)  usually contains a single polypeptide chain. 
B)  may show a sigmoid dependence on substrate concentration. 
C)  is not subject to regulation of its activity. 
D)  often catalyzes a reaction near the end of a pathway. 
E)  is normally subject to irreversible inhibition.

Question 20

Binding of substrate to the active site of an enzyme is

Accepted Answer

A)  reversible. 
B)  irreversible. 
C)  noncompetitive. 
D)  coupled. 
E)  allosteric. 
A)  reversible. 
B)  irreversible. 
C)  noncompetitive. 
D)  coupled. 
E)  allosteric.

Exam 8: Energy, Enzymes, and Metabolism

Enzymes are highly sensitive to pH and temperature because

If Δ\DeltaΔ G for a reaction is positive, the reaction

Metabolism is organized into pathways that are linked in which of the following ways?

The capacity for change is known as _______.

Which of the following statements about enzymes is true?

The sum total of all the chemical reactions in a living structure is called its

Which of the following statements is (are) inconsistent with the first and second laws of thermodynamics?

The rate of a chemical reaction in a cell is the measure of how

Environmental conditions that affect enzyme function include

In the presence of alcohol dehydrogenase, the rate of reduction of acetaldehyde to ethanol increases as the concentration of acetaldehyde is increased. Eventually, the rate of the reaction reaches a maximum, at which point further increases in the concentration of acetaldehyde have no effect. Why?

Many enzymes require ATP and ADP for a reaction to occur. They temporarily bind to and then release from the substrate to participate in other reactions. ATP and ADP are considered

Which of the following statements about allosteric regulators is true?

The second law of thermodynamics states that the _______, or disorder, of the universe is constantly increasing.

Water held back by a dam represents what kind of energy?

A noncompetitive inhibitor inhibits binding of a substrate to an enzyme by

Lactose intolerance is due to the

Fireflies

An allosteric enzyme

Binding of substrate to the active site of an enzyme is

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