Unit 3 Cellular Energetics

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Unit 3 Cellular Energetics


Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 

Which of the following describe(s) some aspect of metabolism?
a.
synthesis of macromolecules
b.
breakdown of macromolecules
c.
control of enzyme activity
d.
A and B only
e.
A, B, and C
 

 2. 

Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
a.
catalysis
b.
metabolism
c.
anabolism
d.
dehydration
e.
catabolism
 

 3. 

Which of the following statements correctly describe(s) catabolic pathways?
a.
They do not depend on enzymes.
b.
They consume energy to build up polymers from monomers.
c.
They release energy as they degrade polymers to monomers.
d.
They lead to the synthesis of catabolic compounds.
e.
both A and B
 

 4. 

Which of the following is (are) true for anabolic pathways?
a.
They do not depend on enzymes.
b.
They are highly regulated sequences of chemical reactions.
c.
They consume energy to build up polymers from monomers.
d.
They release energy as they degrade polymers to monomers.
e.
both B and C
 

 5. 

Which of the following is a statement of the first law of thermodynamics?
a.
Energy cannot be created or destroyed.
b.
The entropy of the universe is decreasing.
c.
The entropy of the universe is constant.
d.
Kinetic energy is stored energy that results from the specific arrangement of matter.
e.
Energy cannot be transferred or transformed.
 

 6. 

The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following is an important consequence of the first law?
a.
The energy content of an organism is constant.
b.
The organism ultimately must obtain all of the necessary energy for life from its environment.
c.
The entropy of an organism decreases with time as the organism grows in complexity.
d.
Organisms are unable to transform energy.
e.
Life does not obey the first law of thermodynamics.
 

 7. 

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?
a.
Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time.
b.
Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is balanced by an increase in the entropy of the universe.
c.
Living organisms do not follow the laws of thermodynamics.
d.
As a consequence of growing, organisms create more disorder in their environment than the decrease in entropy associated with their growth.
e.
Living organisms are able to transform energy into entropy.
 

 8. 

Whenever energy is transformed, there is always an increase in the
a.
free energy of the system.
b.
free energy of the universe.
c.
entropy of the system.
d.
entropy of the universe.
e.
enthalpy of the universe.
 

 9. 

Which of the following statements is a logical consequence of the second law of thermodynamics?
a.
If the entropy of a system increases, there must be a corresponding decrease in the entropy of the universe.
b.
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.
c.
Every energy transfer requires activation energy from the environment.
d.
Every chemical reaction must increase the total entropy of the universe.
e.
Energy can be transferred or transformed, but it cannot be created or destroyed.
 

 10. 

Which of the following statements correctly describe(s) some aspect of energy in living organisms?
a.
Living organisms can convert energy among several different forms.
b.
Living organisms can use energy to do work.
c.
Organisms expend energy in order to decrease their entropy
d.
A and B only
e.
A, B, and C
 

 11. 

The organization of organisms has become increasingly complex with time. This statement
a.
is consistent with the second law of thermodynamics.
b.
requires that due to evolution, the entropy of the universe increased.
c.
is based on the fact that organisms function as closed systems.
d.
A and B only
e.
A, B, and C
 

 12. 

The mathematical expression for the change in free energy of a system is: G = H – TS. Which of the following is (are) incorrect?
a.
S is the change in entropy, a measure of randomness.
b.
H is the change in enthalpy, the energy available to do work.
c.
G is the change in free energy.
d.
T is the absolute temperature.
e.
both A and B
 

 13. 

What is the change in free energy of a system at chemical equilibrium?
a.
slightly increasing
b.
greatly increasing
c.
slightly decreasing
d.
greatly decreasing
e.
no net change
 

 14. 

Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?
a.
a reaction in which the free energy at equilibrium is higher than the energy content at any point away from equilibrium
b.
a chemical reaction in which the entropy change in the reaction is just balanced by an opposite entropy change in the cell's surroundings
c.
an endergonic reaction in an active metabolic pathway where the energy for that reaction is supplied only by heat from the environment
d.
a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive
e.
There is no possibility of having chemical equilibrium in any living cell.
 

 15. 

Which of the following shows the correct changes in thermodynamic properties for a chemical reaction in which amino acids are linked to form a protein?
a.
+H, +S, +G
b.
+H, -S, -G
c.
+H, -S, +G
d.
-H, -S, +G
e.
-H, +S, +G
 

 16. 

When glucose monomers are joined together by glycosidic linkages to form a cellulose polymer, the changes in free energy, total energy, and entropy are as follows:
a.
+G, +H, +S
b.
+G, +H, -S
c.
+G, -H, -S
d.
-G, +H, +S
e.
-G, -H, -S
 

 17. 

A chemical reaction that has a positive G is correctly described as
a.
endergonic.
b.
endothermic.
c.
enthalpic.
d.
spontaneous.
e.
exothermic.
 

 18. 

Why is ATP an important molecule in metabolism?
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.
A and B only
e.
A, B and C
 

 19. 

The hydrolysis of ATP to ADP and inorganic phosphate (ATP + H2O ADP + Pi )
a.
has a G of about -7 kcal/mol under standard conditions.
b.
involves hydrolysis of a terminal phosphate bond of ATP.
c.
can occur spontaneously under appropriate conditions.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 20. 

When 10,000 molecules of ATP are hydrolyzed to ADP and in a test tube, about twice as much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?
a.
Cells are open systems, but a test tube is a closed system.
b.
Cells are less efficient at heat production than nonliving systems.
c.
The hydrolysis of ATP in a cell produces different chemical products than does the reaction in a test tube.
d.
The reaction in cells must be catalyzed by enzymes, but the reaction in a test tube does not need enzymes.
e.
Cells convert some of the energy of ATP hydrolysis into other forms of energy besides heat.
 

 21. 

ATP generally energizes a cellular process by
a.
releasing heat upon hydrolysis.
b.
acting as a catalyst.
c.
coupling free energy released by ATP hydrolysis to free energy needed by other reactions.
d.
breaking a high-energy bond.
e.
binding directly to the substrate(s) of the enzyme.
 

 22. 

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways?
a.
feedback regulation
b.
bioenergetics
c.
energy coupling
d.
entropy
e.
cooperativity
 

 23. 

Which of the following statements is true concerning catabolic pathways?
a.
They combine molecules into more energy-rich molecules.
b.
They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.
c.
They are endergonic.
d.
They are spontaneous and do not need enzyme catalysis.
e.
They build up complex molecules such as protein from simpler compounds.
 

 24. 

Which of the following statements regarding ATP is (are) correct?
a.
ATP serves as a main energy shuttle inside cells.
b.
ATP drives endergonic reactions in the cell by the enzymatic transfer of the phosphate group to specific reactants.
c.
The regeneration of ATP from ADP and phosphate is an endergonic reaction.
d.
A and B only
e.
A, B, and C
 

 25. 

Which of the following statements is (are) true about enzyme-catalyzed reactions?
a.
The reaction is faster than the same reaction in the absence of the enzyme.
b.
The free energy change of the reaction is the same as the reaction in the absence of the enzyme.
c.
The reaction always goes in the direction toward chemical equilibrium.
d.
A and B only
e.
A, B, and C
 

 26. 

How can one increase the rate of a chemical reaction?
a.
Increase the activation energy needed.
b.
Cool the reactants.
c.
Decrease the concentration of the reactants.
d.
Add a catalyst.
e.
Increase the entropy of the reactants.
 

 27. 

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in
a.
bringing glucose and fructose together to form sucrose.
b.
the release of water from sucrose as the bond between glucose and fructose is broken.
c.
breaking the bond between glucose and fructose and forming new bonds from the atoms of water.
d.
production of water from the sugar as bonds are broken between the glucose monomers.
e.
utilization of water as a covalent bond is formed between glucose and fructose to form sucrase.
 

 28. 

Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's
a.
entropy.
b.
activation energy.
c.
endothermic level.
d.
heat content.
e.
free-energy content.
 

 29. 

A solution of starch at room temperature does not readily decompose to form a solution of simple sugars because
a.
the starch solution has less free energy than the sugar solution.
b.
the hydrolysis of starch to sugar is endergonic.
c.
the activation energy barrier for this reaction cannot be surmounted.
d.
starch cannot be hydrolyzed in the presence of so much water.
e.
starch hydrolysis is nonspontaneous.
 

 30. 

An enzyme catalyzes a reaction by
a.
supplying the energy to speed up a reaction.
b.
lowering the energy of activation of a reaction.
c.
lowering the G of a reaction.
d.
changing the equilibrium of a spontaneous reaction.
e.
increasing the amount of free energy of a reaction.
 

 31. 

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?
a.
-40 kcal/mol
b.
-20 kcal/mol
c.
0 kcal/mol
d.
+20 kcal/mol
e.
+40 kcal/mol
 

 32. 

The active site of an enzyme is the region that
a.
binds allosteric regulators of the enzyme.
b.
is involved in the catalytic reaction of the enzyme.
c.
binds the products of the catalytic reaction.
d.
is inhibited by the presence of a coenzyme or a cofactor.
e.
both A and B
 

 33. 

According to the induced fit hypothesis of enzyme catalysis, which of the following is CORRECT?
a.
The binding of the substrate depends on the shape of the active site.
b.
Some enzymes change their structure when activators bind to the enzyme.
c.
A competitive inhibitor can outcompete the substrate for the active site.
d.
The binding of the substrate changes the shape of the enzyme's active site.
e.
The active site creates a microenvironment ideal for the reaction.
 

 34. 

Many different things can alter enzyme activity. Which of the following underlie all types of enzyme regulation?
a.
changes in the activation energy of the reaction
b.
changes in the active site of the enzyme
c.
changes in the free energy of the reaction
d.
A and B only
e.
A, B, and C
 
 
Refer to the figure below to answer the following questions.

nar001-1.jpg

 

 35. 

Which curve was most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
a.
curve 1
b.
curve 2
c.
curve 3
d.
curve 4
e.
curve 5
 

 36. 

As temperature decreases, the rate of an enzyme-catalyzed reaction also decreases. Which of the following explain(s) why this occurs?
a.
Fewer substrates have sufficient energy to get over the activation energy barrier.
b.
Motion in the active site of the enzyme is slowed, thus slowing the catalysis of the enzyme.
c.
The motion of the substrate molecules decreases, allowing them to bind more easily to the active site.
d.
A and B only
e.
A, B, and C
 

 37. 

What is a nonprotein "helper" of an enzyme molecule called?
a.
accessory enzyme
b.
allosteric group
c.
coenzyme
d.
functional group
e.
enzyme activator
 

 38. 

Which of the following is true of enzymes?
a.
Enzymes may require a nonprotein cofactor or ion for catalysis to take place.
b.
Enzyme function is reduced if the three-dimensional structure or conformation of an enzyme is altered.
c.
Enzyme function is influenced by physical and chemical environmental factors such as pH and temperature.
d.
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
e.
All of the above are true of enzymes.
 
 
The following questions are based on the reaction A + B C + D shown in the figure below.

nar002-2.jpg
 

 39. 

Which of the following terms best describes the reaction?
a.
endergonic
b.
exergonic
c.
anabolic
d.
allosteric
e.
nonspontaneous
 

 40. 

Which of the following represents the G of the reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 41. 

Which of the following would be the same in an enzyme-catalyzed or noncatalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 42. 

Which of the following bests describes the reaction?
a.
negative G, spontaneous
b.
positive G, nonspontaneous
c.
positive G, exergonic
d.
negative G, endergonic
e.
G of zero, chemical equilibrium
 

 43. 

Which of the following represents the difference between the free-energy content of the reaction and the free-energy content of the products?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 44. 

Which of the following represents the activation energy required for the enzyme-catalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 45. 

Which of the following represents the activation energy required for a noncatalyzed reaction?
a.
a
b.
b
c.
c
d.
d
e.
e
 

 46. 

Which best describes the reaction?
a.
The amount of free energy initially present in the reactants is indicated by "a."
b.
The amount of free energy present in the products is indicated by "e."
c.
The amount of free energy released as a result of the noncatalyzed reaction is indicated by "c."
d.
The amount of free energy released as a result of the catalyzed reaction is indicated by "d."
e.
The difference between "b" and "c" is the activation energy added by the presence of the enzyme.
 

 47. 

Assume that the reaction has a G of -5.6 kcal/mol. Which of the following would be true?
a.
The reaction could be coupled to power an endergonic reaction with a G of +6.2 kcal/mol.
b.
The reaction could be coupled to power an exergonic reaction with a G of +8.8 kcal/mol.
c.
The reaction would result in a decrease in entropy (S) and an increase in the total energy content (H) of the system.
d.
The reaction would result in an increase in entropy (S) and a decrease in the total energy content (H) of the system.
e.
The reaction would result in products (C + D) with a greater free-energy content than in the initial reactants (A + B).
 
 
Use the information below to answer the following questions.

A series of enzymes catalyze the reaction XYZA. 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.

 

 48. 

Substance A functions as
a.
a coenzyme.
b.
an allosteric inhibitor.
c.
the substrate.
d.
an intermediate.
e.
a competitive inhibitor.
 

 49. 

The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is known as
a.
metabolic inhibition.
b.
feedback inhibition.
c.
allosteric inhibition.
d.
noncooperative inhibition.
e.
reversible inhibition.
 

 50. 

Which of the following statements is true regarding enzyme cooperativity?
a.
A multi-enzyme complex contains all the enzymes of a metabolic pathway.
b.
A product of a pathway serves as a competitive inhibitor of an early enzyme in the pathway.
c.
A substrate molecule bound to an active site affects the active site of several subunits.
d.
Several substrate molecules can be catalyzed by the same enzyme.
e.
A substrate binds to an active site and inhibits cooperation between enzymes in a pathway.
 

 51. 

How does a non-competitive inhibitor decrease the rate of an enzyme reaction?
a.
by binding at the active site of the enzyme
b.
by changing the structure of the enzyme
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
 

 52. 

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
a.
anabolic pathways
b.
catabolic pathways
c.
fermentation pathways
d.
thermodynamic pathways
e.
bioenergetic pathways
 

 53. 

What is the term used for the metabolic pathway in which glucose (C6H12O6) is degraded to carbon dioxide (CO2) and water?
a.
cellular respiration
b.
glycolysis
c.
fermentation
d.
citric acid cycle
e.
oxidative phosphorylation
 

 54. 

Which of the following statements concerning the metabolic degradation of glucose (C6H12O6) to carbon dioxide (CO2) and water is (are) true?
a.
The breakdown of glucose to carbon dioxide and water is exergonic.
b.
The breakdown of glucose to carbon dioxide and water has a free energy change of -686 kcal/mol.
c.
The breakdown of glucose to carbon dioxide and water involves oxidation-reduction or redox reactions.
d.
Only A and B are correct.
e.
A, B, and C are correct.
 

 55. 

Which of the following statements is (are) correct about an oxidation-reduction (or redox) reaction?
a.
The molecule that is reduced gains electrons.
b.
The molecule that is oxidized loses electrons.
c.
The molecule that is reduced loses electrons.
d.
The molecule that is oxidized gains electrons.
e.
Both A and B are correct.
 

 56. 

Which statement is not correct with regard to redox (oxidation-reduction) reactions?
a.
A molecule is reduced if it loses electrons.
b.
A molecule is oxidized if it loses electrons.
c.
An electron donor is called a reducing agent.
d.
An electron acceptor is called an oxidizing agent.
e.
Oxidation and reduction always go together.
 

 57. 

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction
a.
gains electrons and gains energy.
b.
loses electrons and loses energy.
c.
gains electrons and loses energy.
d.
loses electrons and gains energy.
e.
neither gains nor loses electrons, but gains or loses energy.
 

 58. 

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy?
a.
The covalent bonds in organic molecules are higher energy bonds than those in water and carbon dioxide.
b.
Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O)..
c.
The oxidation of organic compounds can be used to make ATP.
d.
The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds.
e.
The covalent bond in O2 is unstable and easily broken by electrons from organic molecules.
 

 59. 

Which of the following statements describes the results of this reaction?

C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy

a.
C6H12O6 is oxidized and O2 is reduced.
b.
O2 is oxidized and H2O is reduced.
c.
CO2 is reduced and O2 is oxidized.
d.
C6H12O6is reduced and CO2 is oxidized.
e.
O2 is reduced and CO2 is oxidized.
 

 60. 

When a glucose molecule loses a hydrogen atom (not a hydrogen ion) as the result of an oxidation-reduction reaction, the molecule becomes
a.
dehydrogenated.
b.
hydrogenated.
c.
oxidized.
d.
reduced.
e.
an oxidizing agent.
 

 61. 

Which of the following statements about NAD+ is false?
a.
NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.
b.
NAD+ has more chemical energy than NADH.
c.
NAD+ is reduced by the action of dehydrogenases.
d.
NAD+ can receive electrons for use in oxidative phosphorylation.
e.
In the absence of NAD+, glycolysis cannot function.
 

 62. 

In order for NAD+ to remove electrons from glucose or other organic molecules, which of the following must be true?
a.
The organic molecule or glucose must be negatively charged in order to reduce the positively charged NAD+.
b.
Oxygen must be present to oxidize the NADH produced back to NAD+.
c.
The free energy liberated when electrons are removed from the organic molecules must be greater than the energy required to give the electrons to NAD+.
d.
A and B are both correct.
e.
A, B, and C are all correct.
 

 63. 

Where does glycolysis takes place?
a.
mitochondrial matrix
b.
mitochondrial outer membrane
c.
mitochondrial inner membrane
d.
mitochondrial intermembrane space
e.
cytosol
 
 
The figure below illustrates some of the steps (reactions) of glycolysis in their proper sequence. Each step is lettered. Use these letters to answer the following questions.

nar004-1.jpg

 

 64. 

Which step shows a split of one molecule into two smaller molecules?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 65. 

In which reaction does an intermediate pathway become oxidized?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 66. 

Which step involves an endergonic reaction?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 67. 

Which step consists of a phosphorylation reaction in which ATP is the phosphate source?
a.
A
b.
B
c.
C
d.
D
e.
E
 

 68. 

During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is
a.
transferred to ADP, forming ATP.
b.
transferred directly to ATP.
c.
retained in the pyruvate.
d.
stored in the NADH produced.
e.
used to phosphorylate fructose to form fructose-6-phosphate.
 

 69. 

In addition to ATP, what are the end products of glycolysis?
a.
CO2 and H2O
b.
CO2 and pyruvate
c.
NADH and pyruvate
d.
CO2 and NADH
e.
H2O, FADH2, and citrate
 

 70. 

The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mole and the free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
a.
Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.
b.
Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.
c.
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
d.
There is no CO2 or water produced as products of glycolysis.
e.
Glycolysis consists of many enzymatic reactions, each of which extracts some energy from the glucose molecule.
 

 71. 

Starting with one molecule of glucose, the "net" products of glycolysis are
a.
2 NAD+, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O.
b.
2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O.
c.
2 FADH2, 2 pyruvate, 4 ATP, and 2 H2O.
d.
6 CO2, 6 H2O, 2 ATP, and 2 pyruvate.
e.
6 CO2, 6 H2O, 36 ATP, and 2 citrate.
 

 72. 

A molecule that is phosphorylated
a.
has an increased chemical reactivity; it is primed to do cellular work.
b.
has a decreased chemical reactivity; it is less likely to provide energy for cellular work.
c.
has been oxidized as a result of a redox reaction involving the gain of an inorganic phosphate.
d.
has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate.
e.
has less energy than before its phosphorylation and therefore less energy for cellular work.
 

 73. 

During cellular respiration, acetyl CoA accumulates in which location?
a.
cytosol
b.
mitochondrial outer membrane
c.
mitochondrial inner membrane
d.
mitochondrial intermembrane space
e.
mitochondrial matrix
 

 74. 

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?
a.
2
b.
4
c.
6
d.
8
e.
10
 
 
Refer to the figure below, showing the citric acid cycle, as a guide to answer the following questions.

nar005-1.jpg

 

 75. 

Starting with one molecule of isocitrate and ending with fumarate, what is the maximum number of ATP molecules that could be made through substrate-level phosphorylation?
a.
1
b.
2
c.
11
d.
12
e.
24
 

 76. 

Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a five-carbon amino acid?
a.
succinate
b.
malate
c.
citrate
d.
-ketoglutarate
e.
isocitrate
 

 77. 

Starting with one molecule of citrate and ending with oxaloacetate, how many ATP molecules can be formed from oxidative phosphorylation (chemiosmosis)?
a.
1
b.
3
c.
4
d.
11
e.
12
 

 78. 

How many molecules of carbon dioxide (CO2) would be produced by five turns of the citric acid cycle?
a.
2
b.
5
c.
10
d.
12
e.
60
 

 79. 

How many reduced dinucleotides would be produced with four turns of the citric acid cycle?
a.
1 FADH2 and 4 NADH
b.
2 FADH2 and 8 NADH
c.
4 FADH2 and 12 NADH
d.
1 FAD and 4 NAD+
e.
4 FAD+ and 12 NAD+
 

 80. 

Starting with citrate, how many of the following would be produced with three turns of the citric acid cycle?
a.
1 ATP, 2 CO2, 3 NADH, and 1 FADH2
b.
2 ATP, 2 CO2, 1 NADH, and 3 FADH2
c.
3 ATP, 3 CO2, 3 NADH, and 3 FADH2
d.
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
e.
38 ATP, 6 CO2, 3 NADH, and 12 FADH2
 

 81. 

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
a.
glycolysis and the oxidation of pyruvate to acetyl CoA
b.
oxidation of pyruvate to acetyl CoA and the citric acid cycle
c.
the citric acid cycle and oxidative phosphorylation
d.
oxidative phosphorylation and fermentation
e.
fermentation and glycolysis
 

 82. 

Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?
a.
pyruvate
b.
malate or fumarate
c.
acetyl CoA
d.
-ketoglutarate
e.
succinyl CoA
 

 83. 

Where are the proteins of the electron transport chain located?
a.
cytosol
b.
mitochondrial outer membrane
c.
mitochondrial inner membrane
d.
mitochondrial intermembrane space
e.
mitochondrial matrix
 

 84. 

Which of the following describes the sequence of electron carriers in the electron transport chain, starting with the least electronegative?
a.
ubiquinone (Q), cytochromes (Cyt), FMN, Fe•S
b.
cytochromes (Cyt), FMN, ubiquinone, Fe·S
c.
Fe•S, FMN, cytochromes (Cyt), ubiquinone
d.
FMN, Fe•S, ubiquinone, cytochromes (Cyt)
e.
cytochromes (Cyt), Fe•S, ubiquinone, FMN
 

 85. 

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
a.
NAD+
b.
NADH
c.
ATP
d.
ADP + Pi
e.
FADH2
 

 86. 

Inside an active mitochondrion, most electrons follow which pathway?
a.
glycolysis NADH oxidative phosphorylation ATP oxygen
b.
citric acid cycle FADH2 electron transport chain ATP
c.
electron transport chain citric acid cycle ATP oxygen
d.
pyruvate citric acid cycle ATP NADH oxygen
e.
citric acid cycle NADH electron transport chain oxygen
 

 87. 

During oxidative phosphorylation, H2O is formed. Where does the oxygen for the synthesis of the water come from?
a.
carbon dioxide (CO2)
b.
glucose (C6H12O6)
c.
molecular oxygen (O2)
d.
pyruvate (C3H3O3–)
e.
lactate (C3H5O3–-)
 

 88. 

Which metabolic process is most closely associated with intracellular membranes?
a.
substrate-level phosphorylation
b.
oxidative phosphorylation
c.
glycolysis
d.
the citric acid cycle
e.
alcohol fermentation
 

 89. 

In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + Pi to ATP?
a.
energy released as electrons flow through the electron transport system
b.
energy released from substrate-level phosphorylation
c.
energy released from ATP synthase pumping hydrogen ions against their concentration gradient
d.
energy released from movement of protons through ATP synthase
e.
No external source of energy is required because the reaction is exergonic.
 

 90. 

Energy released by the electron transport chain is used to pump H+ ions into which location?
a.
cytosol
b.
mitochondrial outer membrane
c.
mitochondrial inner membrane
d.
mitochondrial intermembrane space
e.
mitochondrial matrix
 

 91. 

During aerobic cellular respiration, a proton gradient in mitochondria is generated by ____ and used primarily for ____.
a.
the electron transport chain; ATP synthesis
b.
the electron transport chain; substrate-level phosphorylation
c.
glycolysis; production of H2O
d.
fermentation; NAD+ reduction
e.
diffusion of protons; ATP synthesis
 

 92. 

A major function of the mitochondrial inner membrane is the conversion of energy from electrons to the stored energy of the phosphate bond in ATP. To accomplish this function, the inner mitochondrial membrane must have all of the following features except
a.
carrier proteins to accept electrons from NADH.
b.
integral, transverse ATP synthase.
c.
proton pumps embedded in the membrane.
d.
the electron transport chain of proteins.
e.
high permeability to protons.
 

 93. 

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the
a.
formation of ATP.
b.
reduction of NAD+.
c.
restoration of the Na+/K+ balance across the membrane.
d.
creation of a proton gradient.
e.
lowering of pH in the mitochondrial matrix.
 

 94. 

The primary function of the mitochondrion is the production of ATP. To carry out this function, the mitochondrion must have all of the following except
a.
the membrane-bound electron transport chain carrier molecules.
b.
proton pumps embedded in the inner mitochondrial membrane.
c.
enzymes for glycolysis.
d.
enzymes for the citric acid cycle.
e.
mitochondrial ATP synthase.
 

 95. 

How many molecules of carbon dioxide (CO2) would be released from the complete aerobic respiration of a molecule of sucrose (C12H22 O11), a disaccharide?
a.
2
b.
3
c.
6
d.
12
e.
38
 

 96. 

Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration, how many oxygen molecules (O2). are required?
a.
1
b.
2
c.
6
d.
12
e.
38
 

 97. 

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
a.
glycolysis
b.
fermentation
c.
oxidation of pyruvate to acetyl CoA
d.
citric acid cycle
e.
oxidative phosphorylation (chemiosmosis)
 

 98. 

Assume a mitochondrion contains 58 NADH and 19 FADH2. If each of the 77 dinucleotides were used, approximately how many ATP molecules could be generated as a result of oxidative phosphorylation (chemiosmosis)?
a.
36
b.
77
c.
173
d.
212
e.
1102
 

 99. 

Recall that the complete oxidation of a mole of glucose releases 686 kcal of energy (G = -686 kcal/mol). The phosphorylation of ADP to form ATP stores approximately 7.3 kcal per mole of ATP. What is the approximate efficiency of cellular respiration for a "mutant" organism that produces only 29 moles of ATP for every mole of glucose oxidized, rather than the usual 36-38 moles of ATP?
a.
0.4%
b.
25%
c.
30%
d.
40%
e.
60%
 

 100. 

When glucose (C6H12O6) is oxidized to CO2 and water in cellular respiration, approximately 40% of the energy content of glucose is transferred to
a.
the citric acid cycle.
b.
glycolysis.
c.
ATP (adenosine triphosphate).
d.
heat.
e.
oxygen (O2).
 

 101. 

Which of the following normally occurs whether or not oxygen (O2) is present?
a.
glycolysis
b.
fermentation
c.
oxidation of pyruvate to acetyl CoA
d.
citric acid cycle
e.
oxidative phosphorylation (chemiosmosis)
 

 102. 

Which of the following occurs in the cytosol of the cell?
a.
glycolysis and fermentation
b.
fermentation and chemiosmosis
c.
oxidation of pyruvate to acetyl CoA
d.
citric acid cycle
e.
oxidative phosphorylation
 

 103. 

Which metabolic pathway is common to both cellular respiration and fermentation?
a.
the oxidation of pyruvate to acetyl CoA
b.
the citric acid cycle
c.
oxidative phosphorylation
d.
glycolysis
e.
chemiosmosis
 

 104. 

The ATP made during fermentation is generated by which of the following?
a.
the electron transport chain
b.
substrate-level phosphorylation
c.
chemiosmosis
d.
oxidative phosphorylation
e.
aerobic respiration
 

 105. 

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
a.
ATP, CO2and ethanol (ethyl alcohol).
b.
ATP, CO2, and lactate.
c.
ATP, NADH, and pyruvate.
d.
ATP, pyruvate, and oxygen.
e.
ATP, pyruvate, and acetyl CoA.
 

 106. 

The function of both alcohol fermentation and lactic acid fermentation is to
a.
reduce NAD+ to NADH.
b.
reduce FAD+ to FADH2.
c.
oxidize NADH to NAD+.
d.
reduce FADH2 to FAD+.
e.
none of the above
 

 107. 

Which of the following is not true concerning the cellular compartmentation of the steps of respiration or fermentation?
a.
Acetyl CoA is produced only in the mitochondria.
b.
Lactate is produced only in the cytosol.
c.
NADH is produced only in the mitochondria.
d.
FADH2 is produced only in the mitochondria.
e.
ATP is produced in the cytosol and the mitochondria.
 

 108. 

An organism is discovered that consumes a considerable amount of sugar, yet does not gain much weight when denied air. Curiously, the consumption of sugar increases as air is removed from the organism's environment, but the organism seems to thrive even in the absence of air. When returned to normal air, the organism does fine. Which of the following best describes the organism?
a.
It must use a molecule other than oxygen to accept electrons from the electron transport chain.
b.
It is a normal eukaryotic organism.
c.
The organism obviously lacks the citric acid cycle and electron transport chain.
d.
It is an anaerobic organism.
e.
It is a facultative anaerobe.
 

 109. 

You have a friend who lost 7 kg (about 15 pounds) of fat on a "low carb" diet. How did the fat leave her body?
a.
It was released as CO2 and H2O.
b.
Chemical energy was converted to heat and then released.
c.
It was converted to ATP, which weighs much less than fat.
d.
It was broken down to amino acids and eliminated from the body.
e.
It was converted to urine and eliminated from the body.
 

 110. 

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements concerning phosphofructokinase is not true?
a.
It is activated by AMP (derived from ADP).
b.
It is inhibited by ATP.
c.
It is activated by citrate, an intermediate of the citric acid cycle.
d.
It specifically catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, an early step of glycolysis.
e.
It is an allosteric enzyme.
 

 111. 

Organisms that can exist with light as an energy source and an inorganic form of carbon and other raw materials
a.
are called photoautotrophs.
b.
do not exist in nature.
c.
are called heterotrophs.
d.
are best classified as decomposers.
e.
both C and D
 

 112. 

Which type of organism obtains energy by metabolizing molecules produced by other organisms?
a.
autotrophs
b.
heterotrophs
c.
decomposers
d.
B and C
e.
A, B, and C
 

 113. 

The early suggestion that the oxygen (O2) liberated from plants during photosynthesis comes from water was
a.
first proposed by C.B. van Niel of Stanford University.
b.
confirmed by experiments using oxygen-18 (18O).
c.
made following the discovery of photorespiration because of rubisco's sensitivity to oxygen.
d.
A and B
e.
A, B, and C
 

 114. 

If photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen (18O), later analysis will show that all but one of the following compounds produced by the algae contain the 18O label. That one exception is
a.
PGA.
b.
PGAL.
c.
glucose.
d.
RuBP.
e.
O2.
 

 115. 

What is the primary function of the light reactions of photosynthesis?
a.
to produce energy-rich glucose from carbon dioxide and water
b.
to produce ATP and NADPH
c.
to produce NADPH used in respiration
d.
to convert light energy to the chemical energy of PGAL
e.
to use ATP to make glucose
 

 116. 

What are the products of the light reactions that are subsequently used by the Calvin cycle?
a.
oxygen and carbon dioxide
b.
carbon dioxide and RuBP
c.
water and carbon
d.
electrons and photons
e.
ATP and NADPH
 

 117. 

Where does the Calvin cycle take place?
a.
stroma of the chloroplast
b.
thylakoid membrane
c.
cytoplasm surrounding the chloroplast
d.
chlorophyll molecule
e.
outer membrane of the chloroplast
 

 118. 

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are not being absorbed by this pigment?
a.
red and yellow
b.
blue and violet
c.
green and yellow
d.
blue, green, and red
e.
green, blue, and violet
 
 
Use the following information to answer the questions below.

Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light.

 

 119. 

If you ran the same experiment without passing light through a prism, what would you predict?
a.
There would be no difference in results.
b.
The bacteria would be relatively evenly distributed along the algal filaments.
c.
The number of bacteria present would decrease due to an increase in the carbon dioxide concentration.
d.
The number of bacteria present would increase due to an increase in the carbon dioxide concentration.
e.
The number of bacteria would decrease due to a decrease in the temperature of the water.
 

 120. 

What wavelength of light is most effective in driving photosynthesis?
a.
420 mm
b.
475 mm
c.
575 mm
d.
625 mm
e.
730 mm
 

 121. 

All of the events listed below occur in the light reactions of photosynthesis except
a.
oxygen is produced.
b.
NADP+ is reduced to NADPH.
c.
carbon dioxide is incorporated into PGA.
d.
ADP is phosphorylated to yield ATP.
e.
light is absorbed and funneled to reaction-center chlorophyll a.
 

 122. 

Which of the following statements about the light reactions of photosynthesis are true?
a.
The splitting of water molecules provides a source of electrons.
b.
Chlorophyll (and other pigments) absorb light energy, which excites electrons.
c.
ATP is generated by photophosphorylation.
d.
Only A and C are true.
e.
A, B, and C are true.
 

 123. 

All of the following are directly associated with photosystem II except
a.
extraction of hydrogen electrons from the splitting of water.
b.
release of oxygen.
c.
harvesting of light energy by chlorophyll.
d.
NADP+ reductase.
e.
P680 reaction-center chlorophyll.
 

 124. 

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be
a.
to determine if they have thylakoids in the chloroplasts.
b.
to test for liberation of O2 in the light.
c.
to test for CO2 fixation in the dark.
d.
to do experiments to generate an action spectrum.
e.
to test for production of either sucrose or starch.
 

 125. 

Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will have the most direct effect on which of the following processes?
a.
the splitting of water
b.
the absorption of light energy by chlorophyll
c.
the flow of electrons from photosystem II to photosystem I
d.
the synthesis of ATP
e.
the reduction of NADP+
 

 126. 

What does the chemiosmotic process in chloroplasts involve?
a.
establishment of a proton gradient
b.
diffusion of electrons through the thylakoid membrane
c.
reduction of water to produce ATP energy
d.
movement of water by osmosis into the thylakoid space from the stroma
e.
formation of glucose, using carbon dioxide, NADPH, and ATP
 

 127. 

Suppose the interior of the thylakoids of isolated chloroplasts were made acidic and then transferred in the dark to a pH-8 solution. What would be likely to happen?
a.
The isolated chloroplasts will make ATP.
b.
The Calvin cycle will be activated.
c.
Cyclic photophosphorylation will occur.
d.
Only A and B will occur.
e.
A, B, and C will occur.
 

 128. 

In a plant cell, where are the ATP synthase complexes located?
a.
thylakoid membrane
b.
plasma membrane
c.
inner mitochondrial membrane
d.
A and C
e.
A, B, and C
 

 129. 

In mitochondria, chemiosmosis translocates protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis translocates protons from
a.
the stroma to the photosystem II.
b.
the matrix to the stroma.
c.
the stroma to the thylakoid space.
d.
the intermembrane space to the matrix.
e.
ATP synthase to NADP+ reductase.
 

 130. 

Where is the electron transport chain found in plant cells?
a.
thylakoid membranes of chloroplasts
b.
stroma of chloroplasts
c.
inner membrane of mitochondria
d.
matrix of mitochondria
e.
cytoplasm
 

 131. 

Of the following, what do both mitochondria and chloroplasts have in common?
a.
thylakoid membranes
b.
chemiosmosis
c.
ATP synthase
d.
B and C only
e.
A, B, and C
 
 
Refer to the choices to answer the following questions. Each choice may be used once, more than once, or not at all. Indicate whether the following events occur during

A. photosynthesis
B. respiration
C. both photosynthesis and respiration
D. neither photosynthesis nor respiration
 

 132. 

synthesis of ATP by the chemiosmotic mechanism
a.
A
b.
B
c.
C
d.
D
 

 133. 

reduction of oxygen which forms water
a.
A
b.
B
c.
C
d.
D
 

 134. 

the splitting of carbon dioxide to form oxygen gas and carbon compounds
a.
A
b.
B
c.
C
d.
D
 

 135. 

generation of proton gradients across membranes
a.
A
b.
B
c.
C
d.
D
 

 136. 

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?
a.
The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.
b.
The light reactions provide ATP and NADPH to the carbon fixation step of the Calvin cycle, and the cycle provides water and electrons to the light reactions.
c.
The light reactions supply the Calvin cycle with CO2 to produce sugars, and the Calvin cycle supplies the light reactions with sugars to produce ATP.
d.
The light reactions provide the Calvin cycle with oxygen for electron flow, and the Calvin cycle provides the light reactions with water to split.
e.
There is no relationship between the light reactions and the Calvin cycle.
 

 137. 

What is the primary function of the Calvin cycle?
a.
use ATP to release carbon dioxide
b.
use NADPH to release carbon dioxide
c.
split water and release oxygen
d.
transport RuBP out of the chloroplast
e.
synthesize simple sugars from carbon dioxide
 

 138. 

Which statement is false?
a.
Thylakoid membranes contain the photosynthetic pigments.
b.
The O2 released during photosynthesis comes from water.
c.
RuBP is produced during cyclic electron flow in the light reactions of photosynthesis.
d.
The light reactions of photosynthesis provide the energy for the Calvin cycle.
e.
When chlorophyll is reduced, it gains electrons.
 

 139. 

One carbon dioxide molecule reacts in each "turn" of the Calvin cycle. How many turns of the cycle are required for the synthesis of one glucose molecule?
a.
1
b.
2
c.
3
d.
6
e.
12
 

 140. 

All of the following statements are correct regarding the Calvin cycle except:
a.
The energy source utilized is the ATP and NADPH obtained through the light reaction.
b.
These reactions begin soon after sundown and end before sunrise.
c.
The 5-carbon sugar RuBP is constantly being regenerated.
d.
One of the end products is glyceraldehyde phosphate.
e.
Rubisco attaches carbon dioxide to ribulose bisphosphate.
 
 
For the following questions, compare the light reactions with the Calvin cycle of photosynthesis in plants. Use the following key:

A. light reactions alone
B. the Calvin cycle alone
C. both the light reactions and the Calvin cycle
D. neither the light reactions nor the Calvin cycle
E. occurs in the chloroplast but is not part of photosynthesis
 

 141. 

requires ATP
a.
A
b.
B
c.
C
d.
D
e.
E
 

 142. 

produces three-carbon sugars
a.
A
b.
B
c.
C
d.
D
e.
E
 

 143. 

requires glucose
a.
A
b.
B
c.
C
d.
D
e.
E
 

 144. 

What are the substrates (normal reactants) for the enzyme RuBP carboxylase?
a.
CO2 and O2
b.
CO2 and glucose
c.
ATP and NADPH
d.
triose-P, glucose, and CO2
e.
CO2 and ATP
 
 
Use the figure below to answer the following statements.

nar009-1.jpg

 

 145. 

Oxygen would inhibit the CO2 fixation reactions in
a.
cell I only.
b.
cell II only.
c.
neither cell I nor cell II.
d.
both cell I and cell II.
e.
cell I during the night and cell II during the day.
 

 146. 

In which cell would you expect photorespiration?
a.
Cell I
b.
Cell II
c.
Cell I at night
d.
Cell II at night
e.
neither Cell I nor Cell II
 

 147. 

Why are C4 plants able to photosynthesize with no apparent photorespiration?
a.
They do not participate in the Calvin cycle.
b.
They use PEP carboxylase to initially fix CO2.
c.
They are adapted to cold, wet climates.
d.
They conserve water more efficiently.
e.
They exclude oxygen from their tissues.
 

 148. 

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they
a.
fix CO2 into organic acids during the night.
b.
fix CO2 into sugars in the bundle-sheath cells.
c.
fix CO2 into pyruvate in the mesophyll cells.
d.
use the enzyme phosphofructokinase, which outcompetes rubisco for CO2.
e.
use photosystems I and II at night.
 

 149. 

Photorespiration lowers the efficiency of photosynthesis by preventing the formation of
a.
carbon dioxide molecules.
b.
3-phosphoglycerate molecules
c.
ATP molecules.
d.
ribulose bisphosphate molecules.
e.
RuBP carboxylase molecules.
 

 150. 

Plants that fix CO2 into organic acids at night when the stomata are open and carry out the Calvin cycle during the day when the stomata are closed are called
a.
C3 plants.
b.
C4 plants.
c.
CAM plants.
d.
B and C only.
e.
A, B, and C
 


 
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