Question 1

Figure 6.1
-Which of the following is the most correct interpretation of Figure 6.1?

Accepted Answer

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

Question 2

Most cells cannot harness heat to perform work because

Accepted Answer

A)  heat does not involve a transfer of energy. 
B)  cells do not have much heat; they are relatively cool. 
C)  temperature is usually uniform throughout a cell. 
D)  heat can never be used to do work. 
E)  heat must remain constant during work. 
A)  heat does not involve a transfer of energy. 
B)  cells do not have much heat; they are relatively cool. 
C)  temperature is usually uniform throughout a cell. 
D)  heat can never be used to do work. 
E)  heat must remain constant during work.

Question 3

Which of the following best describes enthalpy (H)?

Accepted Answer

A)  the total kinetic energy of a system 
B)  the heat content of a chemical system 
C)  the system's entropy 
D)  the cell's energy equilibrium 
E)  the condition of a cell that is not able to react 
A)  the total kinetic energy of a system 
B)  the heat content of a chemical system 
C)  the system's entropy 
D)  the cell's energy equilibrium 
E)  the condition of a cell that is not able to react

Question 4

The active site of an enzyme is the region that

Accepted Answer

A)  binds allosteric regulators of the enzyme. 
B)  is involved in the catalytic reaction of the enzyme. 
C)  binds noncompetitive inhibitors of the enzyme. 
D)  is inhibited by the presence of a coenzyme or a cofactor. 
A)  binds allosteric regulators of the enzyme. 
B)  is involved in the catalytic reaction of the enzyme. 
C)  binds noncompetitive inhibitors of the enzyme. 
D)  is inhibited by the presence of a coenzyme or a cofactor.

Question 5

In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?

Accepted Answer

A)  The ATP must first have to attach to the tRNA. 
B)  The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. 
C)  The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. 
D)  The tRNA molecule must have to alter its shape in order to be able to fit into the active site with the other two molecules. 
E)  The 3' end of the tRNA must have to be cleaved before it can have an attached amino acid. 
A)  The ATP must first have to attach to the tRNA. 
B)  The binding of the first two molecules must cause a 3-D change that opens another active site on the enzyme. 
C)  The ATP must be hydrolyzed to allow the amino acid to bind to the synthetase. 
D)  The tRNA molecule must have to alter its shape in order to be able to fit into the active site with the other two molecules. 
E)  The 3' end of the tRNA must have to be cleaved before it can have an attached amino acid.

Question 6

When you have a severe fever, what grave consequence may occur if the fever is not controlled?

Accepted Answer

A)  destruction of your enzymes' primary structure 
B)  removal of amine groups from your proteins 
C)  change in the tertiary structure of your enzymes 
D)  removal of the amino acids in the active sites of your enzymes 
E)  binding of your enzymes to inappropriate substrates 
A)  destruction of your enzymes' primary structure 
B)  removal of amine groups from your proteins 
C)  change in the tertiary structure of your enzymes 
D)  removal of the amino acids in the active sites of your enzymes 
E)  binding of your enzymes to inappropriate substrates

Question 7

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

Accepted Answer

A)  catalysis 
B)  metabolism 
C)  anabolism 
D)  dehydration 
E)  catabolism 
A)  catalysis 
B)  metabolism 
C)  anabolism 
D)  dehydration 
E)  catabolism

Question 8

Some bacteria are metabolically active in hot springs because

Accepted Answer

A)  they are able to maintain a lower internal temperature. 
B)  high temperatures make catalysis unnecessary. 
C)  their enzymes have high optimal temperatures. 
D)  their enzymes are completely insensitive to temperature. 
E)  they use molecules other than proteins or RNAs as their main catalysts. 
A)  they are able to maintain a lower internal temperature. 
B)  high temperatures make catalysis unnecessary. 
C)  their enzymes have high optimal temperatures. 
D)  their enzymes are completely insensitive to temperature. 
E)  they use molecules other than proteins or RNAs as their main catalysts.

Question 9

A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases, although they don't 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. 
E)  ATPase activity must be routing calcium ions from the SR to the cytosol, and then to the cell's environment. 
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. 
E)  ATPase activity must be routing calcium ions from the SR to the cytosol, and then to the cell's environment.

Question 10

A system at chemical equilibrium

Accepted Answer

A)  consumes energy at a steady rate. 
B)  releases energy at a steady rate. 
C)  consumes or releases energy, depending on whether it is exergonic or endergonic. 
D)  has zero kinetic energy. 
E)  can do no work. 
A)  consumes energy at a steady rate. 
B)  releases energy at a steady rate. 
C)  consumes or releases energy, depending on whether it is exergonic or endergonic. 
D)  has zero kinetic energy. 
E)  can do no work.

Question 11

Succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, which resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the ratio of succinate to malonic acid reduces the inhibitory effect of malonic acid.
-Based on this information, which of the following is correct?

Accepted Answer

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

Question 12

Figure 6.3 Activity of various enzymes at various temperatures (a) and at various pH (b).
-Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

Accepted Answer

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

Question 13

How might an amino acid change at a site distant from the active site of the enzyme alter the enzyme's substrate specificity?

Accepted Answer

A)  by changing the enzyme's stability 
B)  by changing the enzyme's location in the cell 
C)  by changing the shape of the protein 
D)  by changing the enzyme's pH optimum 
E)  an amino acid change away from the active site cannot alter the enzyme's substrate specificity 
A)  by changing the enzyme's stability 
B)  by changing the enzyme's location in the cell 
C)  by changing the shape of the protein 
D)  by changing the enzyme's pH optimum 
E)  an amino acid change away from the active site cannot alter the enzyme's substrate specificity

Question 14

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

Accepted Answer

A)  The sugar molecule is different. 
B)  The nitrogen-containing base is different. 
C)  The number of phosphates is three instead of one. 
D)  The number of phosphates is three instead of two. 
E)  There is no difference. 
A)  The sugar molecule is different. 
B)  The nitrogen-containing base is different. 
C)  The number of phosphates is three instead of one. 
D)  The number of phosphates is three instead of two. 
E)  There is no difference.

Question 15

Which of the following is true for anabolic pathways?

Accepted Answer

A)  They do not depend on enzymes. 
B)  They are usually highly spontaneous chemical reactions. 
C)  They consume energy to build up polymers from monomers. 
D)  They release energy as they degrade polymers to monomers. 
E)  They consume energy to decrease the entropy of the organism and its environment. 
A)  They do not depend on enzymes. 
B)  They are usually highly spontaneous chemical reactions. 
C)  They consume energy to build up polymers from monomers. 
D)  They release energy as they degrade polymers to monomers. 
E)  They consume energy to decrease the entropy of the organism and its environment.

Question 16

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

Accepted Answer

A)  by binding at the active site of the enzyme 
B)  by changing the shape of the enzyme's active site 
C)  by changing the free-energy change of the reaction 
D)  by acting as a coenzyme for the reaction 
E)  by decreasing the activation energy of the reaction 
A)  by binding at the active site of the enzyme 
B)  by changing the shape of the enzyme's active site 
C)  by changing the free-energy change of the reaction 
D)  by acting as a coenzyme for the reaction 
E)  by decreasing the activation energy of the reaction

Question 17

Why is ATP an important molecule in metabolism?

Accepted Answer

A)  Its hydrolysis provides an input of free energy for exergonic reactions. 
B)  It provides energy coupling between exergonic and endergonic reactions. 
C)  Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. 
D)  Its terminal phosphate bond has higher energy than the other two. 
E)  It is one of the four building blocks for DNA synthesis. 
A)  Its hydrolysis provides an input of free energy for exergonic reactions. 
B)  It provides energy coupling between exergonic and endergonic reactions. 
C)  Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. 
D)  Its terminal phosphate bond has higher energy than the other two. 
E)  It is one of the four building blocks for DNA synthesis.

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 activation energy needed for the noncatalyzed reverse reaction, C + D → A + B, 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

Which of the following 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 
E)  a phospholipid 
A)  a pentose sugar 
B)  a DNA nucleotide 
C)  an RNA nucleotide 
D)  an amino acid with three phosphate groups attached 
E)  a phospholipid

Question 20

A series of enzymes catalyze the reaction 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)  a coenzyme 
B)  an allosteric inhibitor 
C)  a substrate 
D)  an intermediate 
E)  the product 
A)  a coenzyme 
B)  an allosteric inhibitor 
C)  a substrate 
D)  an intermediate 
E)  the product

Exam 6: An Introduction to Metabolism

Figure 6.1 -Which of the following is the most correct interpretation of Figure 6.1?

Most cells cannot harness heat to perform work because

Which of the following best describes enthalpy (H)?

The active site of an enzyme is the region that

When you have a severe fever, what grave consequence may occur if the fever is not controlled?

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

Some bacteria are metabolically active in hot springs because

A system at chemical equilibrium

Figure 6.3 Activity of various enzymes at various temperatures (a) and at various pH (b). -Which curve(s) on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?

How might an amino acid change at a site distant from the active site of the enzyme alter the enzyme's substrate specificity?

What is the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in RNA?

Which of the following is true for anabolic pathways?

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

Why is ATP an important molecule in metabolism?

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 needed for the noncatalyzed reverse reaction, C + D → A + B, in Figure 6.4?

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

A series of enzymes catalyze the reaction 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?

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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