Biology An Australian Focus Bruce Knox Pauline Ladiges Barbara Evans Robert Saint 5th Edition – Test Bank
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Sample Test
Chapter 03 Testbank
Student: ___________________________________________________________________________
1. In
biological systems, energy can be stored as
A. potential energy.
B. kinetic energy.
C. heat.
D. mechanical energy.
E. All of the answers are correct.
2. According
to the first and second laws of thermodynamics
A. energy flows spontaneously from systems with high free
energy to systems with low free energy in a series of step-by-step
transformations.
B. the quantity of energy in the universe is constant but
its quality is not.
C. transformation of potential energy in a biological
system results in the loss of a small amount of energy.
D. energy can be transformed from one form to another, but
can be neither created nor destroyed.
E. energy is lost from systems during energy transformations
resulting in increasing entropy in the universe.
3. In
biological systems, whenever energy is transformed there is always a (an)
A. increase in the entropy in the system.
B. decrease in the free energy in the system.
C. increase in the potential energy in the system.
D. increase in the entropy in the universe.
E. increase in the free energy in the universe.
4. Biological
systems contribute to the increase in entropy in the universe by transforming
A. potential energy into chemical energy.
B. radiant energy into chemical energy.
C. potential energy into kinetic energy.
D. kinetic energy into potential energy.
E. chemical energy into potential energy.
5. Photosynthesis
is summarised in the equation CO2 +
H2O + radiant energy ===> sugars (CH2O) +
O2 + heat. This is an example of
A. an open system where energy and materials are exchanged
with the environment.
B. a closed system with an equilibrium between the
environment and the materials.
C. an open system where energy is exchanged with the
environment but materials are recycled.
D. an open system where energy is conserved but materials
are exchanged with the environment.
E. a closed system where energy and materials are
conserved.
6. When
a biochemical reaction is at equilibrium
A. the rate of the forward reaction is equal to the rate of
the reverse reaction.
B. there is no net change in the ratio of the concentration
of reactants to products.
C. the concentration of the reactants is equal to the
concentration of the products.
D. the rate of the forward reaction is equal to the rate of
the reverse reaction and there is no net change in the ratio of the
concentration of reactants to products.
E. the rate of the forward reaction is equal to the rate of
the reverse reaction and the concentration of the reactants is equal to the
concentration of the products.
7. When
a reversible metabolic reaction is in a state of maximum disorder, the system
contains its maximum
A. potential energy.
B. entropy.
C. free energy.
D. value for Keq.
E. kinetic energy.
8. Spontaneous
biochemical reactions
A. reach equilibrium rapidly.
B. proceed without enzymes.
C. produce products with less free energy than the
reactants.
D. occur when an enzyme lowers the activation energy
required for the reaction.
E. are initiated without the absorption of activation
energy by the reactants.
9. An
exergonic reaction
A. requires energy.
B.
has a negative DG.
1. is
not spontaneous.
D. can be driven by an endergonic reaction.
E. requires heat to proceed.
10.
In cells, non-spontaneous endergonic processes can proceed by
A. lowering the equilibrium constant (Keq).
B. reducing the amount of entropy required.
C. changing the concentration of the reactants.
D. linking them to spontaneous energy-yielding processes.
E. linking them to another endergonic reaction.
11.
Which statement about activation energy is CORRECT?
A. Lowering the activation energy of a reaction increases
the proportion of molecules that have enough energy to react.
B. A catalyst increases the activation energy of the
reactant molecules and allows the reaction to proceed more easily.
C. Activation energy is not needed if the reaction is
exergonic.
D. Increasing the activation energy of a reaction decreases
the amount of the product at equilibrium.
E. Activation energy is the average kinetic energy of the
reactant molecules.
12.
The complete oxidation of glucose in a cell is represented by
the equation
C6H12O6 + 6O2 ====> 6CO2 +
6H2O, DG = –2879 kJ/mol
The value 2879 kJ/mol is the amount of energy
A. converted into ATP.
B. available to convert ADP to ATP.
C. provided to the enzymes involved to lower the activation
energy.
D. required to activate the reaction.
E. released as heat.
13.
Which statement about enzymes is NOT true?
A. The active site of most enzymes is specific for a range
of substrates.
B. Most chemical reactions in a cell require a specific
enzyme.
C. The reactants that are altered by enzymes are called
substrates.
D. Enzymes reduce the activation energy required for a
reaction.
E. Only a small part of the enzyme molecule is involved in
the reaction.
14.
The rate of an enzyme-catalysed reaction can be influenced by
A. temperature.
B. pH.
C. concentration of the reactants.
D. concentration of the products.
E. All of the answers are correct.
15.
The rate of an enzyme-catalysed reaction
A. increases with an increase in enzyme concentration.
B. decreases with an increase in the substrate
concentration.
C. increases in the presence of allosteric inhibitors.
D. decreases in the presence of cofactors.
E. increases with a decrease in the amount of product.
16.
Allosteric mechanisms regulate enzyme activity by
A. adding a phosphate group to an amino acid in the enzyme.
B. changing the 3-D shape of the enzyme.
C. binding organic molecules to the active site of the
enzyme.
D. changing the amino acid composition at the active site.
E. changing the concentration of the enzyme.
17.
A cofactor
A. provides energy for enzyme activity by adding phosphate
residues to particular amino acids (phosphorylation).
B. competes with the substrate to bind to the active site
of an enzyme.
C. controls enzyme activity by regulating expression of the
DNA coding for the enzyme.
D. is an additional molecule or ion that enables the enzyme
to function.
E. is covalently linked to the active site of an enzyme to
increase activity.
18.
The binding of a substrate to the active site of an enzyme
A. is irreversible.
B. may produce changes in the shape of the enzyme.
C. is coupled to the hydrolysis of ATP.
D. requires activation energy.
E. is by the formation of covalent bonds.
19.
The enzyme ‘thermolysin’ has a zinc ion as part of its active
site. This ion destabilises chemical bonds in the substrate by attracting
electrons and is called
1. an
electron carrier.
B. an inhibitor.
C. a coenzyme.
D. a cofactor.
E. a hydrolyase.
20.
Each step in the biochemical reaction A > B > C > D is
catalysed by a specific enzyme. Product D binds to the enzyme that converts B
to C at a specific site that is not part of its active site. The binding of D
to the enzyme decreases the activity of the enzyme. In this biochemical
reaction, substance D is
A. an enzyme-substrate complex.
B. an allosteric inhibitor.
C. a substrate.
D. an enzyme.
E. a cofactor.
21.
Each step in the biochemical reaction A > B > C > D is
catalysed by a specific enzyme. Product D binds to the enzyme that converts B
to C at a specific site that is not part of its active site. The binding of D
to the enzyme decreases the activity of the enzyme. In this biochemical reaction,
substance B functions as
A. an enzyme-substrate complex.
B. an allosteric inhibitor.
C. a substrate.
D. an enzyme.
E. a cofactor.
22.
An example of catabolism would be
A. assembling cellulose from glucose.
B. the light-independent reactions of photosynthesis.
C. anaerobic respiration.
D. transport across membranes.
E. synthesis of glycogen from glucose.
23.
An enzyme catalyses the breakdown of a dipeptide into two amino
acids. There is a release of energy. Terms that could be used to describe the reaction
are
A. hydrolysis and exergonic.
B. oxidation and exergonic.
C. hydrolysis and endergonic.
D. condensation and exergonic.
E. condensation and endergonic.
24.
ATP
A. is the only energy carrier in the cell.
B. drives energetically favourable reactions.
C. gives up its energy in the form of high energy
electrons.
D. often transfers energy from degradative to synthetic
pathways.
E. supplies energy for the diffusion of compounds across
cell membranes.
25.
The reaction NAD+ +
Pi ====> NADH is likely to be catalysed by
1. a
ligase.
B. a transferase.
C. an isomerase.
D. an oxidoreductase.
E. a hydrolyase.
26.
The reduction of a compound involves
A. addition of oxygen.
B. gain of electrons.
C. loss of protons.
D. the conversion of Fe2+ to
Fe3+.
E. removal of hydrogen.
27.
The purpose of the cytochromes in electron transport chains is
to
A. release energy in small quantities without a large loss
to heat.
B. reduce NADH to NAD+.
C. reduce Fe3+ to
Fe2+.
D. convert oxygen to water.
E. recycle ADP.
28.
An electron transport chain consists of three cytochromes with
the following standard redox potentials:
Cytochrome a (Fe3+)/Cytochrome
a (Fe2+) +290
Cytochrome b (Fe3+)/Cytochrome b (Fe2+)
+120
Cytochrome c (Fe3+)/Cytochrome c (Fe2+)
+220
Which cytochrome in the chain is most likely to donate electrons to the final
electron acceptor (e.g. O2)?
A. Cytochrome a (Fe3+)
B. Cytochrome a (Fe2+)
C. Cytochrome b (Fe2+)
D. Cytochrome c (Fe3+)
E. Cytochrome b (Fe 3+)
29.
Which of the following is the best energy fuel for a cell?
A. Glucose, because it has the highest proportion of C–O
bonds.
B. Protein, because it has energy-rich C–N bonds.
C. Lipids, because they have the highest proportion of C–H
bonds.
D. ADP, because it forms ATP.
E. Cytochromes, because they are involved in electron
transport.
30.
Which of the following statements about enzyme catalysis is
CORRECT?
A. The specificity of an enzyme is determined by the amino
acids at the active site.
B. All enzymes operate optimally at pH 7.0.
C. During substrate binding to the active site, formation
of covalent bonds ensures the correct reaction occurs.
D. Enzymes require a metal ion or a cofactor for activity.
E. All of these answers are correct.
31.
The direction of a biological reaction is driven by
A. the concentration of the reactants.
B. the concentration of the products.
C. the energy of the products compared to the energy of the
reactants.
D. the free energy released by the reaction.
E. All of these factors affect the direction of a
biological reaction.
32.
The role of an enzyme in an enzyme-catalysed reaction is to
A. increase the rate at which the substrate is converted to
product.
B. increase the activation energy of the reaction.
C. form an enzyme-substrate complex which cannot be
converted back to free substrate.
D. convert all the substrate to product.
E. All of these are true about enzyme-catalysed reactions.
33.
The specificity of an enzyme is due to
A. the unique amino acid structure of the binding surface
at the active site.
B. the fixed shape of the amino acids at the active site.
C. the specific covalent bonding between the substrate and
the amino acids at the active site.
D. the ability of amino acids distal from the active site
to react with the substrate and correctly align the substrate.
E. All of these answers are correct.
34.
Allosteric enzymes are enzymes that
A. exist in at least two different shapes.
B. require cofactors for activity.
C. are easily phosphorylated and inactivated.
D. use coenzymes for activity.
E. contain metal ions.
35.
The inorganic non-protein components that participate in enzyme
catalysis are known as
A. coenzymes.
B. cofactors.
C. substrates.
D. products.
E. allosteric inhibitors.
36.
Reactions which do not proceed spontaneously and require energy
are called
A. thermodynamic.
B. allosteric.
C. metabolic.
D. exergonic.
E. endergonic.
37.
In the cell, oxidation of fuel molecules involves
A. the removal of electrons in a step-wise process.
B. oxidation of electron carrier molecules.
C. the direct reaction of fuel molecules with oxygen.
D. the addition of electrons in a step-wise process.
E. the compulsory gain or loss of protons in accordance
with the gain or loss of electrons.
38.
ATP is synthesised using
A. gluconeognesis.
B. an irreversible reaction driven by free electrons.
C. the addition of a phosphate group to AMP.
D. protons donated via the electron transport chain.
E. the energy of electrons removed from fuel molecules.
39.
If oxidation can involve the adding of oxygen, removal of
hydrogen or removal of electrons, reduction must therefore involve
A. removing oxygen, electrons or hydrogen.
B. adding oxygen, removing electrons or hydrogen.
C. removing oxygen, adding electrons, removing hydrogen.
D. adding oxygen, electrons or hydrogen.
E. removing oxygen, adding electrons or hydrogen.
40.
When cells oxidise molecules such as fatty acids or glucose,
which molecule generally operates as the electron carrier?
A. ATP
B. NADH
C. DNA
D. RNA
E. FADH
41.
Where are cytochromes located?
A. membranes of prokaryotes, mitochondria of eukaryotes.
B. membranes of eukaryotes, mitochondria of prokaryotes.
C. membranes of both prokaryotes and eukaryotes.
D. mitochondria of both prokaryotes and eukaryotes.
E. chloroplasts.
42.
The proton motive force produces
A. ATP.
B. NADH.
C. RNA.
D. free electrons.
E. protons.
43.
Which of the following does NOT occur as a result of
transferring electrons across the electron transport chain?
A. Creation of an electrochemical gradient
B. Formation of glucose
C. Regeneration of ATP from ADP and Pi
D. Pumping of protons across a proton impermeable membrane
E. Release of free energy
44.
Oxidative phosphorylation occurs in the
A. nucleus.
B. chloroplasts.
C. cell membrane.
D. cytosol.
E. mitochondria.
45.
Which of the following statements about glucose is CORRECT?
A. It is a metastable compound.
B. It has the chemical formula of C6H11O6.
C. It is not a monomer.
D. It consists of a sucrose and a fructose molecule.
E. In a biological sense, energy is extracted from the C-C,
C-H and C-O covalent bonds.
Chapter 03 Testbank Key
1. In
biological systems, energy can be stored as
A. potential energy.
B. kinetic energy.
C. heat.
D. mechanical energy.
E. All of the answers are correct.
Bloom’s: Knowledge
Difficulty: Easy
Learning Objective: 3.1.
Define the terms potential energy and kinetic energy.
Section: Chemical
reactions and life processes depend on energy
2. According
to the first and second laws of thermodynamics
A. energy flows spontaneously from systems with high free
energy to systems with low free energy in a series of step-by-step
transformations.
B. the quantity of energy in the
universe is constant but its quality is not.
C. transformation of potential energy in a biological
system results in the loss of a small amount of energy.
D. energy can be transformed from one form to another, but
can be neither created nor destroyed.
E. energy is lost from systems during energy
transformations resulting in increasing entropy in the universe.
Bloom’s: Knowledge
Difficulty: Easy
Learning Objective: 3.2.
State the first and second laws of thermodynamics.
Section: Chemical
reactions and life processes depend on energy
3. In
biological systems, whenever energy is transformed there is always a (an)
A. increase in the entropy in the system.
B. decrease in the free energy in the system.
C. increase in the potential energy in the system.
D. increase in the entropy in the
universe.
E. increase in the free energy in the universe.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.2.
State the first and second laws of thermodynamics.
Section: Chemical
reactions and life processes depend on energy
4. Biological
systems contribute to the increase in entropy in the universe by transforming
A. potential energy into chemical energy.
B. radiant energy into chemical energy.
C. potential energy into kinetic
energy.
D. kinetic energy into potential energy.
E. chemical energy into potential energy.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.1.
Define the terms potential energy and kinetic energy.
Section: Chemical
reactions and life processes depend on energy
5. Photosynthesis
is summarised in the equation CO2 +
H2O + radiant energy ===> sugars (CH2O) +
O2 + heat. This is an example of
A. an open system where energy and
materials are exchanged with the environment.
B. a closed system with an equilibrium between the
environment and the materials.
C. an open system where energy is exchanged with the
environment but materials are recycled.
D. an open system where energy is conserved but materials
are exchanged with the environment.
E. a closed system where energy and materials are
conserved.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.2.
State the first and second laws of thermodynamics.
Section: Chemical
reactions and life processes depend on energy
6. When
a biochemical reaction is at equilibrium
A. the rate of the forward reaction is equal to the rate of
the reverse reaction.
B. there is no net change in the ratio of the concentration
of reactants to products.
C. the concentration of the reactants is equal to the
concentration of the products.
D. the rate of the forward reaction is
equal to the rate of the reverse reaction and there is no net change in the
ratio of the concentration of reactants to products.
E. the rate of the forward reaction is equal to the rate of
the reverse reaction and the concentration of the reactants is equal to the
concentration of the products.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.3.
Explain the equilibrium process and how enzyme action affects equilibrium.
Section: The equilibrium
state of a reaction determines its available energy
7. When
a reversible metabolic reaction is in a state of maximum disorder, the system
contains its maximum
A. potential energy.
B. entropy.
C. free energy.
D. value for Keq.
E. kinetic energy.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.2.
State the first and second laws of thermodynamics.
Section: Chemical
reactions and life processes depend on energy
8. Spontaneous
biochemical reactions
A. reach equilibrium rapidly.
B. proceed without enzymes.
C. produce products with less free
energy than the reactants.
D. occur when an enzyme lowers the activation energy
required for the reaction.
E. are initiated without the absorption of activation
energy by the reactants.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.4.
Describe the role of free energy (DG) as an indicator of ultimate equilibrium
position.
Section: The equilibrium
state of a reaction determines its available energy
9. An
exergonic reaction
A. requires energy.
B.
has a negative DG.
1. is
not spontaneous.
D.can be driven by an endergonic reaction.
E. requires heat to proceed.
Bloom’s: Knowledge
Difficulty: Easy
Learning Objective: 3.4.
Describe the role of free energy (DG) as an indicator of ultimate equilibrium
position.
Section: The equilibrium
state of a reaction determines its available energy
10.
In cells, non-spontaneous endergonic processes can proceed by
A. lowering the equilibrium constant (Keq).
B. reducing the amount of entropy required.
C. changing the concentration of the reactants.
D. linking them to spontaneous
energy-yielding processes.
E. linking them to another endergonic reaction.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.4.
Describe the role of free energy (DG) as an indicator of ultimate equilibrium
position.
Section: The equilibrium
state of a reaction determines its available energy
11.
Which statement about activation energy is CORRECT?
A. Lowering the activation energy of a
reaction increases the proportion of molecules that have enough energy to
react.
B. A catalyst increases the activation energy of the
reactant molecules and allows the reaction to proceed more easily.
C. Activation energy is not needed if the reaction is
exergonic.
D. Increasing the activation energy of a reaction decreases
the amount of the product at equilibrium.
E. Activation energy is the average kinetic energy of the
reactant molecules.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.4.
Describe the role of free energy (DG) as an indicator of ultimate equilibrium
position.
Section: The equilibrium
state of a reaction determines its available energy
12.
The complete oxidation of glucose in a cell is represented by
the equation
C6H12O6 + 6O2 ====> 6CO2 +
6H2O, DG = –2879 kJ/mol
The value 2879 kJ/mol is the amount of energy
A. converted into ATP.
B. available to convert ADP to ATP.
C. provided to the enzymes involved to lower the activation
energy.
D. required to activate the reaction.
E. released as heat.
Bloom’s: Knowledge
Difficulty: Hard
Learning Objective: 3.7.
Describe the function of ATP, cofactors and coenzymes and explain their role in
biological reactions.
Section: Chemical
reactions drive events in cells
13.
Which statement about enzymes is NOT true?
A. The active site of most enzymes is
specific for a range of substrates.
B. Most chemical reactions in a cell require a specific
enzyme.
C. The reactants that are altered by enzymes are called
substrates.
D. Enzymes reduce the activation energy required for a
reaction.
E. Only a small part of the enzyme molecule is involved in
the reaction.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.5. Define
an enzyme and explain the model of enzyme action, i.e. the lock and key model.
Section: Enzymes are
biological catalysts
14.
The rate of an enzyme-catalysed reaction can be influenced by
A. temperature.
B. pH.
C. concentration of the reactants.
D. concentration of the products.
E. All of the answers are correct.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.6.
List factors that influence enzyme activity.
Section: Enzymes are
biological catalysts
15.
The rate of an enzyme-catalysed reaction
A. increases with an increase in
enzyme concentration.
B. decreases with an increase in the substrate
concentration.
C. increases in the presence of allosteric inhibitors.
D. decreases in the presence of cofactors.
E. increases with a decrease in the amount of product.
Bloom’s: Knowledge
Difficulty: Easy
Learning Objective: 3.6.
List factors that influence enzyme activity.
Section: Enzymes are
biological catalysts
16.
Allosteric mechanisms regulate enzyme activity by
A. adding a phosphate group to an amino acid in the enzyme.
B. changing the 3-D shape of the
enzyme.
C. binding organic molecules to the active site of the
enzyme.
D. changing the amino acid composition at the active site.
E. changing the concentration of the enzyme.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.6.
List factors that influence enzyme activity.
Section: Enzymes are
biological catalysts
17.
A cofactor
A. provides energy for enzyme activity by adding phosphate
residues to particular amino acids (phosphorylation).
B. competes with the substrate to bind to the active site
of an enzyme.
C. controls enzyme activity by regulating expression of the
DNA coding for the enzyme.
D. is an additional molecule or ion
that enables the enzyme to function.
E. is covalently linked to the active site of an enzyme to
increase activity.
Bloom’s: Knowledge
Difficulty: Easy
Learning Objective: 3.7.
Describe the function of ATP, cofactors and coenzymes and explain their role in
biological reactions.
Section: Enzymes are biological
catalysts
18.
The binding of a substrate to the active site of an enzyme
A. is irreversible.
B. may produce changes in the shape of
the enzyme.
C. is coupled to the hydrolysis of ATP.
D. requires activation energy.
E. is by the formation of covalent bonds.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.5.
Define an enzyme and explain the model of enzyme action, i.e. the lock and key
model.
Section: Enzymes are
biological catalysts
19.
The enzyme ‘thermolysin’ has a zinc ion as part of its active
site. This ion destabilises chemical bonds in the substrate by attracting
electrons and is called
1. an
electron carrier.
B. an inhibitor.
C. a coenzyme.
D. a cofactor.
E. a hydrolyase.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.7.
Describe the function of ATP, cofactors and coenzymes and explain their role in
biological reactions.
Section: Enzymes are
biological catalysts
20.
Each step in the biochemical reaction A > B > C > D is
catalysed by a specific enzyme. Product D binds to the enzyme that converts B
to C at a specific site that is not part of its active site. The binding of D
to the enzyme decreases the activity of the enzyme. In this biochemical
reaction, substance D is
A. an enzyme-substrate complex.
B. an allosteric inhibitor.
C. a substrate.
D. an enzyme.
E. a cofactor.
Bloom’s: Comprehension
Difficulty: Medium
Learning Objective: 3.6.
List factors that influence enzyme activity.
Section: Enzymes are
biological catalysts
21.
Each step in the biochemical reaction A > B > C > D is
catalysed by a specific enzyme. Product D binds to the enzyme that converts B
to C at a specific site that is not part of its active site. The binding of D
to the enzyme decreases the activity of the enzyme. In this biochemical reaction,
substance B functions as
A. an enzyme-substrate complex.
B. an allosteric inhibitor.
C. a substrate.
D. an enzyme.
E. a cofactor.
Bloom’s: Comprehension
Difficulty: Medium
Learning Objective: 3.5.
Define an enzyme and explain the model of enzyme action, i.e. the lock and key
model.
Section: Enzymes are
biological catalysts
22.
An example of catabolism would be
A. assembling cellulose from glucose.
B. the light-independent reactions of photosynthesis.
C. anaerobic respiration.
D. transport across membranes.
E. synthesis of glycogen from glucose.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.8.
Name and describe the six major classes of enzymes given in the chapter.
Section: Chemical
reactions drive events in cells
23.
An enzyme catalyses the breakdown of a dipeptide into two amino
acids. There is a release of energy. Terms that could be used to describe the
reaction are
A. hydrolysis and exergonic.
B. oxidation and exergonic.
C. hydrolysis and endergonic.
D. condensation and exergonic.
E. condensation and endergonic.
Bloom’s: Knowledge
Difficulty: Hard
Learning Objective: 3.8.
Name and describe the six major classes of enzymes given in the chapter.
Section: Chemical
reactions drive events in cells
24.
ATP
A. is the only energy carrier in the cell.
B. drives energetically favourable reactions.
C. gives up its energy in the form of high energy
electrons.
D. often transfers energy from
degradative to synthetic pathways.
E. supplies energy for the diffusion of compounds across cell
membranes.
Bloom’s: Knowledge
Difficulty: Hard
Learning Objective: 3.8.
Name and describe the six major classes of enzymes given in the chapter.
Section: Chemical
reactions drive events in cells
25.
The reaction NAD+ +
Pi ====> NADH is likely to be catalysed by
1. a
ligase.
B. a transferase.
C. an isomerase.
D. an oxidoreductase.
E. a hydrolyase.
Bloom’s: Comprehension
Difficulty: Medium
Learning Objective: 3.8.
Name and describe the six major classes of enzymes given in the chapter.
Section: Chemical
reactions drive events in cells
26.
The reduction of a compound involves
A. addition of oxygen.
B. gain of electrons.
C. loss of protons.
D. the conversion of Fe2+ to
Fe3+.
E. removal of hydrogen.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.9.
Describe the processes of oxidation and reduction.
Section: Oxidation and
reduction reactions
27.
The purpose of the cytochromes in electron transport chains is
to
A. release energy in small quantities
without a large loss to heat.
B. reduce NADH to NAD+.
C. reduce Fe3+ to
Fe2+.
D. convert oxygen to water.
E. recycle ADP.
Bloom’s: Knowledge
Difficulty: Hard
Learning Objective: 3.10.
Describe the role of mediators (or biological electron carriers) in the
electron transport chain.
Section: Chemical
reactions drive events in cells
28.
An electron transport chain consists of three cytochromes with
the following standard redox potentials:
Cytochrome a (Fe3+)/Cytochrome
a (Fe2+) +290
Cytochrome b (Fe3+)/Cytochrome b (Fe2+)
+120
Cytochrome c (Fe3+)/Cytochrome c (Fe2+)
+220
Which cytochrome in the chain is most likely to donate electrons to the final
electron acceptor (e.g. O2)?
A. Cytochrome a (Fe3+)
B. Cytochrome a (Fe2+)
C. Cytochrome b (Fe2+)
D. Cytochrome c (Fe3+)
E. Cytochrome b (Fe 3+)
Bloom’s: Application
Difficulty: Hard
Learning Objective: 3.10.
Describe the role of mediators (or biological electron carriers) in the
electron transport chain.
Section: Oxidation and
reduction reactions
29.
Which of the following is the best energy fuel for a cell?
A. Glucose, because it has the highest proportion of C–O
bonds.
B. Protein, because it has energy-rich C–N bonds.
C. Lipids, because they have the
highest proportion of C–H bonds.
D. ADP, because it forms ATP.
E. Cytochromes, because they are involved in electron
transport.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.11.
Describe the molecules that fuel metabolism.
Section: Oxidation and
reduction reactions
30.
Which of the following statements about enzyme catalysis is
CORRECT?
A. The specificity of an enzyme is
determined by the amino acids at the active site.
B. All enzymes operate optimally at pH 7.0.
C. During substrate binding to the active site, formation
of covalent bonds ensures the correct reaction occurs.
D. Enzymes require a metal ion or a cofactor for activity.
E. All of these answers are correct.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.6.
List factors that influence enzyme activity.
Section: Enzymes are
biological catalysts
31.
The direction of a biological reaction is driven by
A. the concentration of the reactants.
B. the concentration of the products.
C. the energy of the products compared to the energy of the
reactants.
D. the free energy released by the reaction.
E. All of these factors affect the
direction of a biological reaction.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.3.
Explain the equilibrium process and how enzyme action affects equilibrium.
Section: The equilibrium
state of a reaction determines its available energy
32.
The role of an enzyme in an enzyme-catalysed reaction is to
A. increase the rate at which the substrate is converted to
product.
B. increase the activation energy of
the reaction.
C. form an enzyme-substrate complex which cannot be
converted back to free substrate.
D. convert all the substrate to product.
E. All of these are true about enzyme-catalysed reactions.
Bloom’s: Knowledge
Difficulty: Medium
Learning Objective: 3.5.
Define an enzyme and explain the model of enzyme action, i.e. the lock and key
model.
Section: Enzymes are
biological catalysts
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