Question 1

If the temperature of a reaction with a F1F1F1S1F1F1F10G of ‒7.1 kJ/mol increases, what will happen to the F1F1F1S1F1F1F10G of the reaction?

Accepted Answer

A)  It will stay the same. 
B)  It will equal zero. 
C)  It will also increase. 
D)  It will decrease. 
E)  Not enough information is provided to make a determination. 
A)  It will stay the same. 
B)  It will equal zero. 
C)  It will also increase. 
D)  It will decrease. 
E)  Not enough information is provided to make a determination.

Question 2

An allosteric inhibitor

Accepted Answer

A)  decreases the concentration of an inactive enzyme. 
B)  changes the shape of an enzyme. 
C)  increases the concentration of a product. 
D)  changes the shape of a substrate. 
E)  increases the concentration of an enzyme-substrate complex. 
A)  decreases the concentration of an inactive enzyme. 
B)  changes the shape of an enzyme. 
C)  increases the concentration of a product. 
D)  changes the shape of a substrate. 
E)  increases the concentration of an enzyme-substrate complex.

Question 3

What explains the sharp drop-off in enzyme activity as the temperature is raised?

Accepted Answer

A)  At high temperatures, substrates cannot bind as easily to the rapidly moving enzyme molecules. 
B)  The enzyme concentration decreases at high temperatures as molecules move into the vapor phase. 
C)  Movement of both substrate and enzyme molecules is so rapid at high temperatures that the residence time of substrates bound to enzyme decreases, which decreases the chances that products can form. 
D)  The enzyme's three-dimensional structure must be intact for catalysis to occur and becomes disrupted at very high temperatures. 
E)  The equilibrium point for an enzyme-catalyzed reaction is shifted toward reactants and away from products at higher temperatures. 
A)  At high temperatures, substrates cannot bind as easily to the rapidly moving enzyme molecules. 
B)  The enzyme concentration decreases at high temperatures as molecules move into the vapor phase. 
C)  Movement of both substrate and enzyme molecules is so rapid at high temperatures that the residence time of substrates bound to enzyme decreases, which decreases the chances that products can form. 
D)  The enzyme's three-dimensional structure must be intact for catalysis to occur and becomes disrupted at very high temperatures. 
E)  The equilibrium point for an enzyme-catalyzed reaction is shifted toward reactants and away from products at higher temperatures.

Question 4

Which statement can be used to explain how the first law of thermodynamics relates to biological systems?

Accepted Answer

A)  Biological systems must take in energy from the surroundings to be able to build complex molecules from smaller precursor molecules. 
B)  In any biological system, the total energy includes the usable energy that can do work and the unusable energy that is lost to disorder. 
C)  Energy moves in and out of biological systems and is transformed from one type to another, but no energy is destroyed or created in the process. 
D)  The amount of energy that a biological system has available to do work is always less than the original amount of energy taken in by the system from its surroundings. 
E)  In a biological system, free energy continually decreases with repeated energy transformations. 
A)  Biological systems must take in energy from the surroundings to be able to build complex molecules from smaller precursor molecules. 
B)  In any biological system, the total energy includes the usable energy that can do work and the unusable energy that is lost to disorder. 
C)  Energy moves in and out of biological systems and is transformed from one type to another, but no energy is destroyed or created in the process. 
D)  The amount of energy that a biological system has available to do work is always less than the original amount of energy taken in by the system from its surroundings. 
E)  In a biological system, free energy continually decreases with repeated energy transformations.

Question 5

The amount of energy needed to start a reaction is known as its _______ energy.

Accepted Answer

The answer of The amount of energy needed to start...

Question 6

The term referring to a reactant in an enzyme-catalyzed reaction is

Accepted Answer

A)  metabolite. 
B)  participant. 
C)  substrate. 
D)  product. 
E)  intermediate. 
A)  metabolite. 
B)  participant. 
C)  substrate. 
D)  product. 
E)  intermediate.

Question 7

Refer to the graph below.   The letter _______ labels the transition state, and the free energy change for this reaction has a _______ value.

Accepted Answer

A)  B; negative 
B)  C; positive 
C)  D; negative 
D)  B; positive 
E)  C; negative 
A)  B; negative 
B)  C; positive 
C)  D; negative 
D)  B; positive 
E)  C; negative

Question 8

A particular enzyme is used to convert substrate A into product B.If you wished to use this enzyme in another reaction with a different substrate, which of the following substrates could theoretically be acted on by the same enzyme?

Accepted Answer

A)  A molecule with the same charge as A 
B)  A molecule with the same molecular weight as A 
C)  A molecule with the same atomic composition as A but with different structure 
D)  A molecule with the same number of carbons as A 
E)  A molecule with the same three-dimensional shape as A 
A)  A molecule with the same charge as A 
B)  A molecule with the same molecular weight as A 
C)  A molecule with the same atomic composition as A but with different structure 
D)  A molecule with the same number of carbons as A 
E)  A molecule with the same three-dimensional shape as A

Question 9

A chemical cross-linking reagent has two reactive ends that can be used to covalently link two different amino acid groups in proteins.The links that result are similar to a disulfide bridge that forms between two cysteine groups.Biochemists use chemical cross-linking reagents to test for conformational changes in proteins because the cross-links often freeze proteins in a single conformation.Which method of increasing reaction rates would be most adversely affected by chemical cross-linking?

Accepted Answer

A)  Metal ion catalysis 
B)  Covalent catalysis 
C)  Acid-base catalysis 
D)  Induced-fit mechanism 
E)  Substrate orientation 
A)  Metal ion catalysis 
B)  Covalent catalysis 
C)  Acid-base catalysis 
D)  Induced-fit mechanism 
E)  Substrate orientation

Question 10

Free energy is

Accepted Answer

A)  enthalpy. 
B)  entropy. 
C)  usable energy. 
D)  always positive. 
E)  always negative. 
A)  enthalpy. 
B)  entropy. 
C)  usable energy. 
D)  always positive. 
E)  always negative.

Question 11

The phosphorylation of glucose to glucose 6-phosphate is a reaction with a F1F1F1S1F1F1F10G of +4.0 kcal/mol.What is required for this reaction to take place?

Accepted Answer

A)  The input of energy from hydrolysis of ATP 
B)  An increase in glucose concentration to push the reaction toward the product 
C)  The coupling of this reaction with an endergonic reaction 
D)  The addition of a noncompetitive inhibitor 
E)  Nothing is required; this is a spontaneous reaction. 
A)  The input of energy from hydrolysis of ATP 
B)  An increase in glucose concentration to push the reaction toward the product 
C)  The coupling of this reaction with an endergonic reaction 
D)  The addition of a noncompetitive inhibitor 
E)  Nothing is required; this is a spontaneous reaction.

Question 12

Refer to the figure below.   Does this figure illustrate both the first and second laws of thermodynamics?

Accepted Answer

A)  No, the figure illustrates the first law of thermodynamics only, because it shows how the amount of energy remains constant during a transformation. 
B)  No, the figure illustrates the second law of thermodynamics only, because it shows how the amount of usable energy decreases as the result of a transformation. 
C)  No, the figure illustrates the second law of thermodynamics only, because both laws cannot operate simultaneously in the same system. 
D)  Yes, the figure illustrates both laws of thermodynamics because both laws state the same basic principle. 
E)  Yes, the figure illustrates both laws of thermodynamics because it shows conservation of total energy and a decrease in usable energy during a transformation. 
A)  No, the figure illustrates the first law of thermodynamics only, because it shows how the amount of energy remains constant during a transformation. 
B)  No, the figure illustrates the second law of thermodynamics only, because it shows how the amount of usable energy decreases as the result of a transformation. 
C)  No, the figure illustrates the second law of thermodynamics only, because both laws cannot operate simultaneously in the same system. 
D)  Yes, the figure illustrates both laws of thermodynamics because both laws state the same basic principle. 
E)  Yes, the figure illustrates both laws of thermodynamics because it shows conservation of total energy and a decrease in usable energy during a transformation.

Question 13

Refer to the figure below.   The figure shows how a histidine group at the active site of an enzyme could function either as a base (left) or as an acid (right).The pKa of histidine is 6.0, which means that at pH 6.0, there are equal numbers of ionized and nonionized histidine groups since a pKa is an acid dissociation constant.With this in mind, what would you expect about the pH sensitivity of enzyme X that uses histidine as a base catalyst compared with enzyme Y that uses histidine as an acid catalyst?

Accepted Answer

A)  Enzyme X and enzyme Y would both have the highest activities at pH 6.0, with lower activities at pH values above and below pH 6.0. 
B)  Enzyme X and enzyme Y would both have lower activities at pH values below 6.0 and higher activities at pH values above 6.0. 
C)  Enzyme X and enzyme Y would both have higher activities at pH values below 6.0 and lower activities at pH values above 6.0. 
D)  Enzyme X would have higher activities below pH 6.0 and lower activities above pH 6.0, while enzyme Y would have lower activities below pH 6.0 and higher activities above pH 6.0. 
E)  Enzyme X would have lower activities below pH 6.0 and higher activities above pH 6.0, while enzyme Y would have higher activities below pH 6.0 and lower activities above pH 6.0. 
A)  Enzyme X and enzyme Y would both have the highest activities at pH 6.0, with lower activities at pH values above and below pH 6.0. 
B)  Enzyme X and enzyme Y would both have lower activities at pH values below 6.0 and higher activities at pH values above 6.0. 
C)  Enzyme X and enzyme Y would both have higher activities at pH values below 6.0 and lower activities at pH values above 6.0. 
D)  Enzyme X would have higher activities below pH 6.0 and lower activities above pH 6.0, while enzyme Y would have lower activities below pH 6.0 and higher activities above pH 6.0. 
E)  Enzyme X would have lower activities below pH 6.0 and higher activities above pH 6.0, while enzyme Y would have higher activities below pH 6.0 and lower activities above pH 6.0.

Question 14

Refer to the graphs below.   The graphs show data collected during the characterization of an enzyme.Which is the most likely source of the enzyme?

Accepted Answer

A)  The heart of a desert mouse 
B)  The stomach of an Arctic fish 
C)  The brain of a tropical shark 
D)  The intestines of an African zebra 
E)  The muscles of a Texas hummingbird 
A)  The heart of a desert mouse 
B)  The stomach of an Arctic fish 
C)  The brain of a tropical shark 
D)  The intestines of an African zebra 
E)  The muscles of a Texas hummingbird

Question 15

Refer to the table below.   A student prepared the table to summarize information she had learned about biological catalysts.Which statement best evaluates the accuracy of the information in the table?

Accepted Answer

A)  The table is accurate as written. 
B)  Information in columns 2 and 3 should be switched. 
C)  Information in columns 2 and 4 should be switched. 
D)  Information in column 1 is incorrect. 
E)  Information in column 5 is incorrect. 
A)  The table is accurate as written. 
B)  Information in columns 2 and 3 should be switched. 
C)  Information in columns 2 and 4 should be switched. 
D)  Information in column 1 is incorrect. 
E)  Information in column 5 is incorrect.

Question 16

Which of the following can participate in an enzymatic reaction as an electron donor or acceptor?

Accepted Answer

A)  Hydrophobic side chain in the active site 
B)  Metal ion bound to amino acid side chains in the active site 
C)  Peptide bonds that are exposed to the active site of an enzyme 
D)  Acidic side chain in the active site 
E)  Carboxyl groups of the enzyme's polypeptide backbone 
A)  Hydrophobic side chain in the active site 
B)  Metal ion bound to amino acid side chains in the active site 
C)  Peptide bonds that are exposed to the active site of an enzyme 
D)  Acidic side chain in the active site 
E)  Carboxyl groups of the enzyme's polypeptide backbone

Question 17

Two amino acids shown to be essential in the catalytic mechanism of phosphohexose isomerase are a histidine and a lysine.These two side chains work together in a reversible series of protonation and deprotonation steps to break one bond in the substrate and form a new one.This is an example of a(n) _______ mechanism of catalysis.

Accepted Answer

The answer of Two amino acids shown to be essential...

Question 18

Refer to the figure below.   A purified enzyme was subjected to changes in a variable (X) as its ability to catalyze its chemical reaction was measured.Based on the shape of the curve, which variable could X be?

Accepted Answer

A)  Time 
B)  Temperature 
C)  Substrate concentration 
D)  Buffer concentration 
E)  Reaction volume 
A)  Time 
B)  Temperature 
C)  Substrate concentration 
D)  Buffer concentration 
E)  Reaction volume

Question 19

Hexokinase is the enzyme that catalyzes the reaction shown below.   To which class of enzymes does hexokinase belong?

Accepted Answer

A)  Oxidoreductases 
B)  Transferases 
C)  Hydrolases 
D)  Lyases 
E)  Ligases 
A)  Oxidoreductases 
B)  Transferases 
C)  Hydrolases 
D)  Lyases 
E)  Ligases

Question 20

Suppose the reaction A F1F1F1S1F1F1F10 B has a large negative F1F1F1S1F1F1F10G.The reaction would proceed _______, at equilibrium _______ would be present, and _______.

Accepted Answer

A)  from A to B; mostly B; insufficient information is given to predict the rate of the reaction 
B)  from B to A; mostly A; the reaction would be slow 
C)  from A to B; mostly B; the reaction would be fast 
D)  from A to B; mostly B; the reaction would be slow 
E)  There is not enough information to answer the question. 
A)  from A to B; mostly B; insufficient information is given to predict the rate of the reaction 
B)  from B to A; mostly A; the reaction would be slow 
C)  from A to B; mostly B; the reaction would be fast 
D)  from A to B; mostly B; the reaction would be slow 
E)  There is not enough information to answer the question.

Exam 8: Energy, Enzymes, and Metabolism

If the temperature of a reaction with a G of ‒7.1 kJ/mol increases, what will happen to the G of the reaction?

An allosteric inhibitor

What explains the sharp drop-off in enzyme activity as the temperature is raised?

Which statement can be used to explain how the first law of thermodynamics relates to biological systems?

The amount of energy needed to start a reaction is known as its _______ energy.

The term referring to a reactant in an enzyme-catalyzed reaction is

Refer to the graph below. The letter _______ labels the transition state, and the free energy change for this reaction has a _______ value.

A particular enzyme is used to convert substrate A into product B.If you wished to use this enzyme in another reaction with a different substrate, which of the following substrates could theoretically be acted on by the same enzyme?

Free energy is

The phosphorylation of glucose to glucose 6-phosphate is a reaction with a G of +4.0 kcal/mol.What is required for this reaction to take place?

Refer to the figure below. Does this figure illustrate both the first and second laws of thermodynamics?

Refer to the graphs below. The graphs show data collected during the characterization of an enzyme.Which is the most likely source of the enzyme?

Refer to the table below. A student prepared the table to summarize information she had learned about biological catalysts.Which statement best evaluates the accuracy of the information in the table?

Which of the following can participate in an enzymatic reaction as an electron donor or acceptor?

Refer to the figure below. A purified enzyme was subjected to changes in a variable (X) as its ability to catalyze its chemical reaction was measured.Based on the shape of the curve, which variable could X be?

Hexokinase is the enzyme that catalyzes the reaction shown below. To which class of enzymes does hexokinase belong?

Suppose the reaction A  B has a large negative G.The reaction would proceed _______, at equilibrium _______ would be present, and _______.

Studying Life

Small Molecules and the Chemistry of Life

Proteins, Carbohydrates, and Lipids

Nucleic Acids and the Origin of Life

Cells: the Working Units of Life

Cell Membranes

Cell Communication and Multicellularity

Pathways That Harvest Chemical Energy

Photosynthesis: Energy From Sunlight

The Cell Cycle and Cell Division

Inheritance, Genes, and Chromosomes

Dna and Its Role in Heredity

From Dna to Protein: Gene Expression

Gene Mutation and Molecular Medicine

Regulation of Gene Expression

Genomes

Recombinant Dna and Biotechnology

Mechanisms of Evolution

Reconstructing and Using Phylogenies

Speciation

Evolution of Genes and Genomes

The History of Life on Earth

Bacteria, Archaea, and Viruses

The Origin and Diversification of Eukaryotes

Plants Without Seeds: From Water to Land

The Evolution of Seed Plants

The Evolution and Diversity of Fungi

Animal Origins and the Evolution of Body Plans

Protostome Animals

Deuterostome Animals

The Plant Body

Transport in Plants

Plant Nutrition

Regulation of Plant Growth

Reproduction in Flowering Plants

Plant Responses to Environmental Challenges

Physiology, Homeostasis, and Temperature Regulation

Animal Hormones

Immunology: Animal Defense Systems

Animal Reproduction

Animal Development

Neurons, Glia, and Nervous Systems

Sensory Systems

The Mammalian Nervous System: Structure and Higher Functions

Musculoskeletal Systems

Gas Exchange

Circulatory Systems

Nutrition, Digestion, and Absorption

Salt and Water Balance and Nitrogen Excretion

Animal Behavior

The Physical Environment and Biogeography of Life

Populations

Species Interactions

Communities

Ecosystems

A Changing Biosphere

Filters

Refer to the graph below. The letter _ labels the transition state, and the free energy change for this reaction has a _ value.

Suppose the reaction A  B has a large negative G.The reaction would proceed ___, at equilibrium _ would be present, and _____.