Question 1

A chemical reaction that has a positive ΔG is best described as ________.

Accepted Answer

A)  endergonic 
B)  enthalpic 
C)  spontaneous 
D)  exergonic 
A)  endergonic 
B)  enthalpic 
C)  spontaneous 
D)  exergonic

Question 2

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

Accepted Answer

A)  -40 kcal/mol 
B)  -20 kcal/mol 
C)  -10 kcal/mol 
D)  +20 kcal/mol 
A)  -40 kcal/mol 
B)  -20 kcal/mol 
C)  -10 kcal/mol 
D)  +20 kcal/mol

Question 3

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

Accepted Answer

A)  Additional substrate will be formed. 
B)  The reaction will change from endergonic to exergonic. 
C)  The free energy of the system will change. 
D)  Nothing; the reaction will stay at equilibrium. 
A)  Additional substrate will be formed. 
B)  The reaction will change from endergonic to exergonic. 
C)  The free energy of the system will change. 
D)  Nothing; the reaction will stay at equilibrium.

Question 4

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 5

Characterization of the complete three-dimensional structure of a newly purified protein suggests that it catalyzes the breakdown of a large substrate. The protein consists of a single polypeptide chain. It has a large pocket that appears to be the binding site for the substrate and a smaller indentation that appears to be the binding site for a regulatory molecule. What do these structural observations suggest about the mechanism by which the activity of this protein is likely regulated?

Accepted Answer

A)  It is probably an enzyme that is regulated by noncompetitive inhibition. 
B)  It is probably a multi-subunit enzyme that is regulated by allosteric regulation. 
C)  It is probably an enzyme that is regulated by competitive inhibition. 
D)  It is probably an enzyme that is regulated by cooperativity. 
A)  It is probably an enzyme that is regulated by noncompetitive inhibition. 
B)  It is probably a multi-subunit enzyme that is regulated by allosteric regulation. 
C)  It is probably an enzyme that is regulated by competitive inhibition. 
D)  It is probably an enzyme that is regulated by cooperativity.

Question 6

Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst?

Accepted Answer

A)  The catalyzed reaction will be slower. 
B)  The catalyzed reaction will have the same ∆G. 
C)  The catalyzed reaction will have higher activation energy. 
D)  The catalyzed reaction will consume all of the catalyst. 
A)  The catalyzed reaction will be slower. 
B)  The catalyzed reaction will have the same ∆G. 
C)  The catalyzed reaction will have higher activation energy. 
D)  The catalyzed reaction will consume all of the catalyst.

Question 7

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 8

Which of the following statements is a logical 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 there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. 
D)  Each chemical reaction in an organism must increase 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 there is an increase in the energy of a system, there must be a corresponding decrease in the energy of the rest of the universe. 
D)  Each chemical reaction in an organism must increase the total entropy of the universe.

Question 9

Why is the ΔG of ATP hydrolysis in the cell about twice as great as the ΔG of ATP hydrolysis in a test tube under standard conditions?

Accepted Answer

A)  A cell is an open system, whereas a test tube is a closed system. 
B)  ATP hydrolysis in a test tube releases more heat than ATP hydrolysis associated with cellular metabolism. 
C)  Reactant and product concentrations in the test tube are different from those in the cell. 
D)  ATP hydrolysis in cells is catalyzed by enzymes, whereas the reaction in a test tube occurs spontaneously. 
A)  A cell is an open system, whereas a test tube is a closed system. 
B)  ATP hydrolysis in a test tube releases more heat than ATP hydrolysis associated with cellular metabolism. 
C)  Reactant and product concentrations in the test tube are different from those in the cell. 
D)  ATP hydrolysis in cells is catalyzed by enzymes, whereas the reaction in a test tube occurs spontaneously.

Question 10

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?

Accepted Answer

A)  ATP is more abundant near the plasma membrane. 
B)  They can more readily encounter and phosphorylate other membrane proteins. 
C)  Membrane localization lowers the activation energy of the phosphorylation reaction. 
D)  They flip back and forth across the membrane to access target proteins on either side. 
A)  ATP is more abundant near the plasma membrane. 
B)  They can more readily encounter and phosphorylate other membrane proteins. 
C)  Membrane localization lowers the activation energy of the phosphorylation reaction. 
D)  They flip back and forth across the membrane to access target proteins on either side.

Question 11

Which of the following statements describes an example of cooperativity associated with enzyme regulation?

Accepted Answer

A)  binding of the end product of a metabolic pathway to the first enzyme in the pathway to inhibit the enzyme 
B)  one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway 
C)  binding a substrate to one subunit of a tetramer stimulates faster binding of substrate to each of the other three subunits 
D)  binding of an ATP molecule along with another substrate molecule in the active site of the enzyme 
A)  binding of the end product of a metabolic pathway to the first enzyme in the pathway to inhibit the enzyme 
B)  one enzyme in a metabolic pathway passing its product to act as a substrate for the next enzyme in the pathway 
C)  binding a substrate to one subunit of a tetramer stimulates faster binding of substrate to each of the other three subunits 
D)  binding of an ATP molecule along with another substrate molecule in the active site of the enzyme

Question 12

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.

Accepted Answer

A)  exergonic; spontaneous 
B)  exergonic; endergonic 
C)  free energy; entropy 
D)  work; energy 
A)  exergonic; spontaneous 
B)  exergonic; endergonic 
C)  free energy; entropy 
D)  work; energy

Question 13

Which of the following statements describes the first law of thermodynamics?

Accepted Answer

A)  Energy cannot be created or destroyed. 
B)  The entropy of the universe is decreasing. 
C)  The entropy of the universe is constant. 
D)  Energy cannot be transferred or transformed. 
A)  Energy cannot be created or destroyed. 
B)  The entropy of the universe is decreasing. 
C)  The entropy of the universe is constant. 
D)  Energy cannot be transferred or transformed.

Question 14

Which of the following types of reactions would decrease the entropy within a cell?

Accepted Answer

A)  anabolic reactions 
B)  hydrolysis 
C)  digestion 
D)  catabolic reactions 
A)  anabolic reactions 
B)  hydrolysis 
C)  digestion 
D)  catabolic reactions

Question 15

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 captured to store energy as more ATP. 
C)  It is used to generate ADP from nucleotide precursors. 
D)  It is lost to the environment. 
A)  It is used to power yet more cellular work. 
B)  It is captured to store energy as more ATP. 
C)  It is used to generate ADP from nucleotide precursors. 
D)  It is lost to the environment.

Question 16

Which of the following metabolic processes can occur without a net influx of energy from some other process?

Accepted Answer

A)  ADP +   → ATP + H₂O 
B)  C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O 
C)  6CO₂ + 6H₂0 → C₆H₁₂O₆ + 6O₂ 
D)  Amino acids → Protein 
A)  ADP +   → ATP + H₂O 
B)  C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O 
C)  6CO₂ + 6H₂0 → C₆H₁₂O₆ + 6O₂ 
D)  Amino acids → Protein

Question 17

In a metabolic pathway, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. Which of the following statements correctly describes the role played by molecules described in the reaction?

Accepted Answer

A)  Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction. 
B)  Succinate dehydrogenase is the enzyme, and malonic acid is the substrate in the reaction. 
C)  Succinate is the substrate, and fumarate is the product in the reaction. 
D)  Fumarate is the product, and malonic acid is a noncompetitive inhibitor in the reaction. 
A)  Succinate dehydrogenase is the enzyme, and fumarate is the substrate in the reaction. 
B)  Succinate dehydrogenase is the enzyme, and malonic acid is the substrate in the reaction. 
C)  Succinate is the substrate, and fumarate is the product in the reaction. 
D)  Fumarate is the product, and malonic acid is a noncompetitive inhibitor in the reaction.

Question 18

In addition to activating or inhibiting enzymes through allosteric regulation, what other means does a cell 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 19

Which of the following is the most correct interpretation of the figure?

Accepted Answer

A)  Energy from catabolism can be used directly for performing cellular work. 
B)  ADP +   ᵢ are a set of molecules that store energy for catabolism. 
C)  ATP is a molecule that acts as an intermediary to store energy for cellular work. 
D)    ᵢ acts as a shuttle molecule to move energy from ATP to ADP. 
A)  Energy from catabolism can be used directly for performing cellular work. 
B)  ADP +   ᵢ are a set of molecules that store energy for catabolism. 
C)  ATP is a molecule that acts as an intermediary to store energy for cellular work. 
D)    ᵢ acts as a shuttle molecule to move energy from ATP to ADP.

Question 20

Which of the following statements is true for all exergonic reactions?

Accepted Answer

A)  The products have more total energy than the reactants. 
B)  The reaction proceeds with a net release of free energy. 
C)  The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. 
D)  A net input of energy from the surroundings is required for the reactions to proceed. 
A)  The products have more total energy than the reactants. 
B)  The reaction proceeds with a net release of free energy. 
C)  The reaction goes only in a forward direction: all reactants will be converted to products, but no products will be converted to reactants. 
D)  A net input of energy from the surroundings is required for the reactions to proceed.

Exam 8: An Introduction to Metabolism

A chemical reaction that has a positive ΔG is best described as ________.

During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?

If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?

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

Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst?

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

Which of the following statements is a logical consequence of the second law of thermodynamics?

Why is the ΔG of ATP hydrolysis in the cell about twice as great as the ΔG of ATP hydrolysis in a test tube under standard conditions?

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?

Which of the following statements describes an example of cooperativity associated with enzyme regulation?

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as ________ is to ________.

Which of the following statements describes the first law of thermodynamics?

Which of the following types of reactions would decrease the entropy within a cell?

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

Which of the following metabolic processes can occur without a net influx of energy from some other process?

In addition to activating or inhibiting enzymes through allosteric regulation, what other means does a cell use to control enzymatic activity?

Which of the following is the most correct interpretation of the figure?

Which of the following statements is true for all exergonic reactions?

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

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

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

Filters

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as is to .