Question 1

How do cells use the ATP cycle illustrated in the figure?

Accepted Answer

A)  Cells use the cycle to recycle ADP and phosphate. 
B)  Cells use the cycle to recycle energy released by ATP hydrolysis. 
C)  Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP hydrolysis. 
D)  Cells use the cycle primarily to generate heat. 
A)  Cells use the cycle to recycle ADP and phosphate. 
B)  Cells use the cycle to recycle energy released by ATP hydrolysis. 
C)  Cells use the cycle to recycle ADP, phosphate, and the energy released by ATP hydrolysis. 
D)  Cells use the cycle primarily to generate heat.

Question 2

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

Accepted Answer

A)  Living organisms do not obey the second law of thermodynamics, which states that the entropy of an organism increases with each energy transformation. 
B)  The decrease in entropy is associated with growth of an organism. As a consequence of growth, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their increased complexity. 
C)  As a consequence of growth, the decrease in entropy of the organism is associated with a corresponding decrease in the entropy of the universe. 
D)  Living organisms are able to transform chemical energy into entropy. 
A)  Living organisms do not obey the second law of thermodynamics, which states that the entropy of an organism increases with each energy transformation. 
B)  The decrease in entropy is associated with growth of an organism. As a consequence of growth, organisms cause a greater increase in entropy in their environment than the decrease in entropy associated with their increased complexity. 
C)  As a consequence of growth, the decrease in entropy of the organism is associated with a corresponding decrease in the entropy of the universe. 
D)  Living organisms are able to transform chemical energy into entropy.

Question 3

Which of the following statements about enzyme function is true?

Accepted Answer

A)  Enzyme function is generally increased if the three-dimensional structure or conformation of an enzyme is altered. 
B)  Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. 
C)  Enzymes increase the rate of chemical reactions by lowering activation energy barriers. 
D)  Enzymes increase the rate of chemical reactions by providing activation energy to the substrate. 
A)  Enzyme function is generally increased if the three-dimensional structure or conformation of an enzyme is altered. 
B)  Enzyme function is independent of physical and chemical environmental factors such as pH and temperature. 
C)  Enzymes increase the rate of chemical reactions by lowering activation energy barriers. 
D)  Enzymes increase the rate of chemical reactions by providing activation energy to the substrate.

Question 4

Most cells cannot harness heat to perform work because ________.

Accepted Answer

A)  heat is not a form of energy 
B)  temperature is usually uniform throughout a cell 
C)  heat can never be used to do work 
D)  heat must remain constant during work 
A)  heat is not a form of energy 
B)  temperature is usually uniform throughout a cell 
C)  heat can never be used to do work 
D)  heat must remain constant during work

Question 5

Which of the following terms most precisely describes the cellular process of breaking down large molecules into smaller ones?

Accepted Answer

A)  catabolism (catabolic pathways) 
B)  metabolism 
C)  anabolism (anabolic pathways) 
D)  dehydration 
A)  catabolism (catabolic pathways) 
B)  metabolism 
C)  anabolism (anabolic pathways) 
D)  dehydration

Question 6

Which of the following statements about anabolic pathways is true?

Accepted Answer

A)  They are usually spontaneous chemical reactions. 
B)  They consume energy to build up polymers from monomers. 
C)  They release energy by degrading polymers to monomers. 
D)  They decrease the entropy of the organism and its environment. 
A)  They are usually spontaneous chemical reactions. 
B)  They consume energy to build up polymers from monomers. 
C)  They release energy by degrading polymers to monomers. 
D)  They decrease the entropy of the organism and its environment.

Question 7

Which of the following graphs most likely describes the effect of pH on the function of the enzyme catalase in human cells? Note: The x-axis is pH and the y-axis is enzyme activity.

Accepted Answer

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

Question 8

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. What role does malonic acid play with respect to succinate dehydrogenase?

Accepted Answer

A)  Malonic acid is a competitive inhibitor. 
B)  Malonic acid blocks the binding of fumarate. 
C)  Malonic acid is a noncompetitive inhibitor. 
D)  Malonic acid is an allosteric regulator. 
A)  Malonic acid is a competitive inhibitor. 
B)  Malonic acid blocks the binding of fumarate. 
C)  Malonic acid is a noncompetitive inhibitor. 
D)  Malonic acid is an allosteric regulator.

Question 9

Use the following information to answer the question below.
(a)
 
                        $\text { Temperature }\left({ }^{\circ} \mathrm{C}\right) \rightarrow$

(b)
 
                                          $\mathrm{PH} \longrightarrow$
Activity of various enzymes at various temperatures (a)and at various pH (b)
Which temperature and pH profile curves on the graphs are most likely associated with an enzyme isolated from a human stomach where conditions are strongly acid?

Accepted Answer

A)  curves 1 and 4 
B)  curves 1 and 5 
C)  curves 2 and 4 
D)  curves 3 and 4 
A)  curves 1 and 4 
B)  curves 1 and 5 
C)  curves 2 and 4 
D)  curves 3 and 4

Question 10

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 11

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases, although they do not often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10⁻⁷ while the concentration in the SR is 10⁻², then how is the ATPase acting?

Accepted Answer

A)  ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR. 
B)  ATPase activity must be transferring   ᵢ to the SR to enable this to occur. 
C)  ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient. 
D)  ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient. 
A)  ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR. 
B)  ATPase activity must be transferring   ᵢ to the SR to enable this to occur. 
C)  ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient. 
D)  ATPase activity must be opening a channel for the calcium ions to diffuse back into the SR along the concentration gradient.

Question 12

A series of enzymes catalyze the reactions in the metabolic pathway X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?

Accepted Answer

A)  an allosteric inhibitor 
B)  a substrate 
C)  an intermediate 
D)  the product 
A)  an allosteric inhibitor 
B)  a substrate 
C)  an intermediate 
D)  the product

Question 13

Use the following information to answer the question below.
 
The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following represents the activation energy required for the non-enzyme-catalyzed reaction in the figure?

Accepted Answer

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

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

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 16

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 may be used to form a phosphorylated intermediate. 
D)  It enters the nucleus to be incorporated in a nucleotide. 
A)  It is secreted as waste. 
B)  It is used only to regenerate more ATP. 
C)  It may be used to form a phosphorylated intermediate. 
D)  It enters the nucleus to be incorporated in a nucleotide.

Question 17

A series of enzymes catalyze the reactions in the metabolic pathway X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. With respect to the enzyme that converts X to Y, substance A functions as ________.

Accepted Answer

A)  an allosteric inhibitor 
B)  the substrate 
C)  an intermediate 
D)  a competitive inhibitor 
A)  an allosteric inhibitor 
B)  the substrate 
C)  an intermediate 
D)  a competitive inhibitor

Question 18

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.

Question 19

________ is a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway.

Accepted Answer

A)  Allosteric inhibition 
B)  Cooperative inhibition 
C)  Feedback inhibition 
D)  Metabolic inhibition 
A)  Allosteric inhibition 
B)  Cooperative inhibition 
C)  Feedback inhibition 
D)  Metabolic inhibition

Question 20

Which of the following statements describes a central role that ATP plays in cellular metabolism?

Accepted Answer

A)  Hydrolysis of ATP provides an input of free energy for exergonic reactions. 
B)  ATP provides energy coupling between exergonic and endergonic reactions. 
C)  Hydrolysis of the terminal phosphate group stores free energy that is used for cellular work. 
D)  Its terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules. 
A)  Hydrolysis of ATP provides an input of free energy for exergonic reactions. 
B)  ATP provides energy coupling between exergonic and endergonic reactions. 
C)  Hydrolysis of the terminal phosphate group stores free energy that is used for cellular work. 
D)  Its terminal phosphate bond is stronger than most covalent bonds in other biological macromolecules.

Exam 8: An Introduction to Metabolism

How do cells use the ATP cycle illustrated in the figure?

Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of an organism. How does this relate to the second law of thermodynamics?

Which of the following statements about enzyme function is true?

Most cells cannot harness heat to perform work because ________.

Which of the following terms most precisely describes the cellular process of breaking down large molecules into smaller ones?

Which of the following statements about anabolic pathways is true?

Which of the following graphs most likely describes the effect of pH on the function of the enzyme catalase in human cells? Note: The x-axis is pH and the y-axis is enzyme activity.

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

A series of enzymes catalyze the reactions in the metabolic pathway X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?

Use the following information to answer the question below. The figure illustrates the energy states associated with the reaction A + B ↔ C + D. Which of the following represents the activation energy required for the non-enzyme-catalyzed reaction in the figure?

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

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

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 for all exergonic reactions?

________ is a regulatory mechanism in which the end product of a metabolic pathway inhibits an enzyme that catalyzes an early step in the pathway.

Which of the following statements describes a central role that ATP plays in cellular metabolism?

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

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