Question 1

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because

Accepted Answer

A)  the starch solution has less free energy than the sugar solution. 
B)  the hydrolysis of starch to sugar is endergonic. 
C)  the activation energy barrier for this reaction cannot easily be surmounted at room temperature. 
D)  starch cannot be hydrolyzed in the presence of so much water. 
E)  starch hydrolysis is nonspontaneous. 
A)  the starch solution has less free energy than the sugar solution. 
B)  the hydrolysis of starch to sugar is endergonic. 
C)  the activation energy barrier for this reaction cannot easily be surmounted at room temperature. 
D)  starch cannot be hydrolyzed in the presence of so much water. 
E)  starch hydrolysis is nonspontaneous. C

Question 2

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms,

Accepted Answer

A)  has occurred in accordance with the laws of thermodynamics. 
B)  has caused an increase in the entropy of the planet. 
C)  has been made possible by expending Earth's energy resources. 
D)  has occurred in accordance with the laws of thermodynamics, by expending Earth's energy resources and causing an increase in the entropy of the planet. 
E)  violates the laws of thermodynamics because Earth is a closed system. 
A)  has occurred in accordance with the laws of thermodynamics. 
B)  has caused an increase in the entropy of the planet. 
C)  has been made possible by expending Earth's energy resources. 
D)  has occurred in accordance with the laws of thermodynamics, by expending Earth's energy resources and causing an increase in the entropy of the planet. 
E)  violates the laws of thermodynamics because Earth is a closed system. A

Question 3

Figure 6.2 Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant.
-In Figure 6.2, why does the reaction rate plateau at higher reactant concentrations?

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 activation energy for the reaction increases with reactant concentration. 
E)  The rate of the reverse reaction increases with reactant concentration. 
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 activation energy for the reaction increases with reactant concentration. 
E)  The rate of the reverse reaction increases with reactant concentration. B

Question 4

Mutations that result in single amino acid substitutions in an enzyme

Accepted Answer

A)  cannot affect the activity or properties of the enzyme. 
B)  will almost always destroy the activity of the enzyme. 
C)  will often change the substrate specificity of the enzyme. 
D)  may change the enzyme's optimal temperature or optimal pH. 
E)  may, in rare cases, cause the enzyme to run reactions in reverse. 
A)  cannot affect the activity or properties of the enzyme. 
B)  will almost always destroy the activity of the enzyme. 
C)  will often change the substrate specificity of the enzyme. 
D)  may change the enzyme's optimal temperature or optimal pH. 
E)  may, in rare cases, cause the enzyme to run reactions in reverse.

Question 5

Which of the following statements describes enzyme cooperativity?

Accepted Answer

A)  A multienzyme complex contains all the enzymes of a metabolic pathway. 
B)  A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. 
C)  A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits. 
D)  Several substrate molecules can be catalyzed by the same enzyme. 
E)  A substrate binds to an active site and inhibits cooperation between enzymes in a pathway. 
A)  A multienzyme complex contains all the enzymes of a metabolic pathway. 
B)  A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway. 
C)  A substrate molecule bound to an active site of one subunit promotes substrate binding to the active site of other subunits. 
D)  Several substrate molecules can be catalyzed by the same enzyme. 
E)  A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.

Question 6

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Accepted Answer

A)  denaturation of the enzyme 
B)  allosteric inhibition 
C)  competitive inhibition 
D)  saturation of the enzyme activity 
E)  insufficient cofactors 
A)  denaturation of the enzyme 
B)  allosteric inhibition 
C)  competitive inhibition 
D)  saturation of the enzyme activity 
E)  insufficient cofactors

Question 7

Which of the following statements regarding enzymes is true?

Accepted Answer

A)  Enzymes increase the rate of a reaction by making the reaction more exergonic. 
B)  Enzymes increase the rate of a reaction by lowering the activation energy barrier. 
C)  Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. 
D)  Enzymes change the equilibrium point of the reactions they catalyze. 
E)  Enzymes make the rate of a reaction independent of substrate concentrations. 
A)  Enzymes increase the rate of a reaction by making the reaction more exergonic. 
B)  Enzymes increase the rate of a reaction by lowering the activation energy barrier. 
C)  Enzymes increase the rate of a reaction by reducing the rate of reverse reactions. 
D)  Enzymes change the equilibrium point of the reactions they catalyze. 
E)  Enzymes make the rate of a reaction independent of substrate concentrations.

Question 8

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4.
   Figure 6.4
-Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 6.4?

Accepted Answer

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

Question 9

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

Accepted Answer

A)  It is used to power yet more cellular work. 
B)  It is used to store energy as more ATP. 
C)  It is used to generate ADP from nucleotide precursors. 
D)  It is lost to the environment. 
E)  It is transported to specific organs such as the brain. 
A)  It is used to power yet more cellular work. 
B)  It is used to store energy as more ATP. 
C)  It is used to generate ADP from nucleotide precursors. 
D)  It is lost to the environment. 
E)  It is transported to specific organs such as the brain.

Question 10

Which of the following is true of metabolism in its entirety in all organisms?

Accepted Answer

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

Question 11

Which of the following is an example of cooperativity?

Accepted Answer

A)  the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway 
B)  one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway 
C)  a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three 
D)  the effect of increasing temperature on the rate of an enzymatic reaction 
E)  binding of an ATP molecule along with one of the substrate molecules in an active site 
A)  the binding of an end product of a metabolic pathway to the first enzyme that acts in the pathway 
B)  one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway 
C)  a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three 
D)  the effect of increasing temperature on the rate of an enzymatic reaction 
E)  binding of an ATP molecule along with one of the substrate molecules in an active site

Question 12

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

Accepted Answer

A)  It is secreted as waste. 
B)  It is used only to regenerate more ATP. 
C)  It is added to water and excreted as a liquid. 
D)  It may be used to form a phosphorylated intermediate. 
E)  It enters the nucleus and affects gene expression. 
A)  It is secreted as waste. 
B)  It is used only to regenerate more ATP. 
C)  It is added to water and excreted as a liquid. 
D)  It may be used to form a phosphorylated intermediate. 
E)  It enters the nucleus and affects gene expression.

Question 13

For the hydrolysis of ATP to ADP + ℗i, the free-energy change is -7.3 kcal/mol under standard conditions (1 M concentration of both reactants and products). In the cellular environment, however, the free-energy change is about -13 kcal/mol. What can we conclude about the free-energy change for the formation of ATP from ADP and ℗i under cellular conditions?

Accepted Answer

A)  It is +7.3 kcal/mol. 
B)  It is less than +7.3 kcal/mol. 
C)  It is about +13 kcal/mol. 
D)  It is greater than +13 kcal/mol. 
E)  The information given is insufficient to deduce the free-energy change. 
A)  It is +7.3 kcal/mol. 
B)  It is less than +7.3 kcal/mol. 
C)  It is about +13 kcal/mol. 
D)  It is greater than +13 kcal/mol. 
E)  The information given is insufficient to deduce the free-energy change.

Question 14

Which of the following statements is true concerning catabolic pathways?

Accepted Answer

A)  They combine molecules into more energy-rich molecules. 
B)  They supply energy, primarily in the form of ATP, for the cell's work. 
C)  They are endergonic. 
D)  They are spontaneous and do not need enzyme catalysis. 
E)  They build up complex molecules such as protein from simpler compounds. 
A)  They combine molecules into more energy-rich molecules. 
B)  They supply energy, primarily in the form of ATP, for the cell's work. 
C)  They are endergonic. 
D)  They are spontaneous and do not need enzyme catalysis. 
E)  They build up complex molecules such as protein from simpler compounds.

Question 15

Whenever energy is transformed, there is always an increase in the

Accepted Answer

A)  free energy of the system. 
B)  free energy of the universe. 
C)  entropy of the system. 
D)  entropy of the universe. 
E)  enthalpy of the universe. 
A)  free energy of the system. 
B)  free energy of the universe. 
C)  entropy of the system. 
D)  entropy of the universe. 
E)  enthalpy of the universe.

Question 16

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4.
   Figure 6.4
-Which of the following terms best describes the forward reaction in Figure 6.4?

Accepted Answer

A)  endergonic, ∆G > 0 
B)  exergonic, ∆G  0 
E)  chemical equilibrium, ∆G = 0 
A)  endergonic, ∆G > 0 
B)  exergonic, ∆G  0 
E)  chemical equilibrium, ∆G = 0

Question 17

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

Accepted Answer

A)  The energy content of an organism is constant. 
B)  The organism ultimately must obtain all of the necessary energy for life from its environment. 
C)  The entropy of an organism decreases with time as the organism grows in complexity. 
D)  Organisms grow by converting energy into organic matter. 
E)  Life does not obey the first law of thermodynamics. 
A)  The energy content of an organism is constant. 
B)  The organism ultimately must obtain all of the necessary energy for life from its environment. 
C)  The entropy of an organism decreases with time as the organism grows in complexity. 
D)  Organisms grow by converting energy into organic matter. 
E)  Life does not obey the first law of thermodynamics.

Question 18

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4.
   Figure 6.4
-Which of the following represents the ΔG of the reaction in Figure 6.4?

Accepted Answer

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

Question 19

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's

Accepted Answer

A)  entropy. 
B)  activation energy. 
C)  endothermic level. 
D)  equilibrium point. 
E)  free-energy content. 
A)  entropy. 
B)  activation energy. 
C)  endothermic level. 
D)  equilibrium point. 
E)  free-energy content.

Question 20

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

Exam 6: An Introduction to Metabolism

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because

Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms,

Figure 6.2 Rate of an enzyme-catalyzed reaction as a function of varying reactant concentration, with the concentration of enzyme constant. -In Figure 6.2, why does the reaction rate plateau at higher reactant concentrations?

Mutations that result in single amino acid substitutions in an enzyme

Which of the following statements describes enzyme cooperativity?

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

Which of the following statements regarding enzymes is true?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4. Figure 6.4 -Which of the following represents the activation energy required for the enzyme-catalyzed reaction in Figure 6.4?

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

Which of the following is true of metabolism in its entirety in all organisms?

Which of the following is an example of cooperativity?

When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?

Which of the following statements is true concerning catabolic pathways?

Whenever energy is transformed, there is always an increase in the

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4. Figure 6.4 -Which of the following terms best describes the forward reaction in Figure 6.4?

For living organisms, which of the following is an important consequence of the first law of thermodynamics?

The following questions are based on the reaction A + B ↔ C + D shown in Figure 6.4. Figure 6.4 -Which of the following represents the ΔG of the reaction in Figure 6.4?

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's

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

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development, Stem Cells, and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

Early Life and the Diversification of Prokaryotes

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition, Nutrition, and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons, Synapses, and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Species Interactions

Ecosystems and Energy

Global Ecology and Conservation Biology

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