Deck 9: Pathways That Harvest Chemical Energy

Question 1

A species of bacteria was cultured in a test tube containing a uniform distribution of glucose but a varying distribution of oxygen.Oxygen was highest near the top of the tube and very low at the bottom.If this bacterial species is incapable of carrying out fermentation or other anaerobic energy-harvesting pathways, which test tube represents the expected growth pattern of the bacterial culture?

A)
B)
C)
D)
E)

Answer 1

A

Question 2

In all cells, glucose catabolism begins with

A) glycolysis.
B) fermentation.
C) pyruvate oxidation.
D) the citric acid cycle.
E) chemiosmosis.

Answer 2

A

Question 3

Refer to the figure below, which provides information about the series of oxidation-reduction reactions that take place via the respiratory chain in the inner mitochondrial membrane. Which statement about the respiratory chain explains the biological importance of the information portrayed in the graph?

A) The extensive folding of the inner mitochondrial membrane provides the space needed to accommodate the large number of proteins making up the respiratory chain.
B) Oxygen serves as the final electron acceptor in the respiratory chain, forming water as a result of its acceptance of electrons that have passed down the chain.
C) With each oxidation-reduction step in the respiratory chain, an electron loses free energy that is captured in a form that the cell can use to perform biological work.
D) NADH and FADH₂ pass their electrons to different carriers in the respiratory chain.
E) The components of the respiratory chain are physically arranged within the mitochondrial membrane in the order of transfer of electrons down the chain.

Answer 3

C

Question 4

The carbon end product of glycolysis is

A) pyruvate.
B) carbon dioxide.
C) ethanol.
D) lactic acid.
E) ATP.

Question 5

The oxidation of malate to oxaloacetate is coupled to the reduction of NAD⁺ to NADH + H⁺.In this process, NAD⁺ is a(n)

A) reducing agent.
B) oxidizing agent.
C) vitamin.
D) phosphate ester.
E) phosphorylating agent.

Question 6

Refer to the figure below, which shows a series of coupled reactions. Which terms belong in the numbered boxes?

A) 1 = reduction; 2 = reduction; 3 = oxidation; 4 = oxidation
B) 1 = oxidation; 2 = oxidation; 3 = reduction; 4 = reduction
C) 1 = reduction; 2 = oxidation; 3 = reduction; 4 = oxidation
D) 1 = oxidation; 2 = reduction; 3 = oxidation; 4 = reduction
E) 1 = oxidation; 2 = reduction; 3 = reduction; 4 = oxidation

Question 7

Which statement about metabolic pathways is false?

A) The rate of the pathway can be altered by activating or inhibiting some key enzymes within the pathway.
B) Metabolic pathways are a series of enzyme-catalyzed reactions.
C) Almost all metabolic pathways are anabolic.
D) Many metabolic pathways are similar in all organisms.
E) Many metabolic pathways are compartmentalized in eukaryotes.

Question 8

NADH

A) is a key electron carrier in redox reactions.
B) requires O₂ to function.
C) is found only in prokaryotes.
D) binds with an acetyl group to form acetyl CoA.
E) detoxifies hydrogen peroxide.

Question 9

Refer to the figure below, which shows an oxidation-reduction reaction that occurs spontaneously. Which statement correctly compares the free energy stored in molecules shown in the figure?

A) The reduced form of B has greater free energy than the reduced form of A.
B) The oxidized form of B has greater free energy than the reduced form of A.
C) The reduced form of A has greater free energy than the oxidized form of A.
D) The oxidized form of B has greater free energy than the reduced form of B.
E) The oxidized form of A has greater free energy than the reduced form of B.

Question 10

Glycolysis converts glucose to pyruvate with the formation of ATP and NADH.This process requires

A) O₂, ATP, and a series of reactions.
B) CO₂, five enzyme-catalyzed reactions, and glucose to begin the series of reactions.
C) pyruvic acid, O₂, and enzymes to oxidize glucose inside the mitochondria.
D) the pyruvate dehydrogenase complex to catalyze the reactions.
E) ten enzyme-catalyzed reactions, with each reaction dependent on the products of the previous reaction.

Question 11

Refer to the figure below, illustrating how two redox reactions are coupled in an energy-harvesting pathway in a cell. Which molecules could serve as compounds X and Y, respectively?

A) ADP and ATP
B) ATP and ADP
C) FADH₂ and FAD
D) NAD⁺ and NADH
E) NADH and NAD⁺

Question 12

Refer to the figure below. How is this molecule involved in the cellular harvesting of energy from glucose oxidation?

A) During the oxidation of glucose in a cell, this molecule is hydrolyzed to release the chemical energy in its phosphate bonds.
B) Electrons are removed from glucose and transferred to this molecule as a means of harvesting energy from glucose's chemical bonds.
C) This molecule transfers electrons to glucose in one step of the cellular glucose oxidation pathway.
D) Energy released during the cellular oxidation of glucose is used to add a phosphate to this molecule.
E) Oxygen accepts electrons from this molecule as the final step in the cellular oxidation of glucose.

Question 13

Refer to the reaction below.
Glyceraldehyde 3-phosphate (G3P) + NAD⁺ + H⁺ + P_i $\rightarrow$ 1,3-bisphosphoglycerate (BPG) + NADH
In this redox reaction, _______ is oxidized and _______ is reduced.

A) G3P; NAD⁺
B) BPG; NADH + H⁺
C) G3P; NADH + H⁺
D) NAD⁺; NADH + H⁺
E) NAD⁺; G3P

Question 14

Refer to the figure below, showing the exergonic reaction that links glycolysis to the citric acid cycle. Which statement about the molecules participating in this cellular reaction is correct?

A) Pyruvate has higher stored free energy than acetyl CoA, and NAD⁺ has the same stored free energy as NADH.
B) Acetyl CoA has higher stored free energy than pyruvate, and NAD⁺ has higher stored free energy than NADH.
C) Pyruvate has higher stored free energy than acetyl CoA, and NAD⁺ has higher stored free energy than NADH.
D) Acetyl CoA has higher stored free energy than pyruvate, and NADH has higher stored free energy than NAD⁺.
E) Pyruvate has higher stored free energy than acetyl CoA, and NADH has higher stored free energy than NAD⁺.

Question 15

Which of the following statements can be used as evidence that living cells follow the same basic principles of chemistry that nonliving systems follow?

A) Cells use three catabolic processes to harvest energy in the chemical bonds of glucose: glycolysis, cellular respiration, and fermentation.
B) Anaerobic oxidation of glucose is incomplete, since oxidation does not proceed completely to carbon dioxide and water, but stops at an intermediate end product.
C) Each step in the oxidation of glucose in a cell is catalyzed by a different enzyme.
D) One mole of glucose burned in a dish releases 686 kcal of heat energy, while a group of cells oxidizing the same quantity of glucose releases the same quantity of energy in a different form.
E) In a cell, different steps in the complete oxidation of glucose are carried out in different cellular compartments.

Question 16

Which process converts glucose to pyruvate, generating a small amount of ATP but no CO₂?

A) Pyruvate oxidation
B) Glycolysis
C) The citric acid cycle
D) The respiratory chain
E) Gluconeogenesis

Question 17

Which statement about metabolic pathways is true?

A) Complex chemical transformations in the cell occur in a single reaction.
B) Each reaction of the pathway requires O₂.
C) In eukaryotes, the pathways exist in the cytoplasm.
D) The pathways vary from organism to organism.
E) Each pathway is regulated by specific enzymes.

Question 18

When a molecule loses hydrogen atoms (as opposed to hydrogen ions), it becomes

A) reduced.
B) oxidized.
C) redoxed.
D) hydrogenated.
E) hydrolyzed.

Question 19

The end result of glycolysis includes the formation of many molecules, including the

A) formation of 38 molecules of ATP.
B) reduction of 8 molecules of NAD⁺ to NADH.
C) formation of 2 molecules of pyruvate.
D) conversion of 1 molecule of glucose to lactic acid.
E) production of carbon dioxide.

Question 20

Refer to the equation below, summarizing a step in lactic acid fermentation. Pyruvate + NADH + H⁺ $\rightarrow$ lactate + NAD⁺
In this reaction, which compound is oxidized and which is reduced?

A) Pyruvate is oxidized and lactate is reduced.
B) NADH is oxidized and lactate is reduced.
C) Pyruvate is reduced and NADH is oxidized.
D) NAD⁺ is reduced and pyruvate is oxidized.
E) Lactate is oxidized and NADH is reduced.

Question 21

The following reaction summarizes the overall chemical change that takes place as the result of electrons transferred along the respiratory chain. The formation of ATP from ADP and P_i requires the input of 7.3 kcal/mol.The respiratory chain can efficiently convert the majority of the free energy released from electrons to the chemical energy of phosphate bonds in ATP molecules, without a lot of wasted energy given off as heat.Which characteristic of the respiratory chain explains how this is possible?

A) The number of components in the respiratory chain
B) The sizes of the components of the respiratory chain
C) The protein nature of many of the components in the respiratory chain
D) The location of the components in the inner mitochondrial membrane
E) The identity of the final electron acceptor at the end of the respiratory chain

Question 22

Some aerobic bacterial species have respiratory chains with fewer components than those in mammalian respiratory chains.Which other characteristic would you expect to differ between these bacteria and mammalian cells?

A) The mechanism of ATP synthase in forming ATP
B) The production of a hydrogen ion gradient across a membrane
C) The arrangement of respiratory proteins in a series to facilitate electron transfer
D) The quantity of ATP synthesized per electron passed down the respiratory chain
E) The free energy change associated with the oxidation of NADH to NAD⁺ by oxygen

Question 23

Which pathways are found in the mitochondrial matrix?

A) Glycolysis and the citric acid cycle
B) Glycolysis and fermentation
C) Pyruvate oxidation and the respiratory chain
D) Pyruvate oxidation and the citric acid cycle
E) Pyruvate oxidation and fermentation

Question 24

Pyruvate oxidation generates

A) acetyl CoA and carbon dioxide.
B) lactic acid and NADH.
C) ethanol and carbon dioxide.
D) citrate and ATP.
E) amino acids and ATP.

Question 25

Which event is not a part of oxidative phosphorylation?

A) Consumption of O₂
B) Formation of ATP
C) Formation of H₂O
D) Formation of carbon dioxide
E) Donation of electrons from FADH₂

Question 26

Refer to the table below, which summarizes similarities and differences between glycolysis and the citric acid cycle in animal cells. A student prepared this table as an aid to her study of these metabolic processes.Which statement best evaluates the accuracy of the student's work?

A) The table is accurate as written.
B) The inputs are not accurate for either glycolysis or the citric acid cycle.
C) The outputs are not accurate for glycolysis.
D) The type of pathway listed for glycolysis is not accurate.
E) The overall energy change is not accurately described for the citric acid cycle.

Question 27

Aerobic organisms exchange air containing O₂ with air containing less O₂ and more CO₂.The CO₂ comes from

A) hydrocarbons and the air.
B) the citric acid cycle.
C) glycolysis.
D) waste products.
E) oxidative phosphorylation.

Question 28

More free energy is harvested during the citric acid cycle than during glycolysis, but only 1 mole of ATP is produced for each mole of acetyl CoA that enters the cycle.Most of the remaining free energy released during the citric acid cycle is

A) used to synthesize GTP.
B) used to reduce electron carriers.
C) lost as heat.
D) used to reduce pyruvate.
E) converted to kinetic energy.

Question 29

In the first reaction of glycolysis, glucose receives a phosphate group from ATP.This reaction is

A) respiration.
B) a redox reaction.
C) exergonic.
D) endergonic.
E) fermentation.

Question 30

In steps 6 through 10 of glycolysis, the conversion of 1 mole of glyceraldehyde 3-phosphate to pyruvate yields 2 moles of ATP.But the oxidation of glucose to pyruvate produces a total of 4 moles of ATP.Where do the remaining 2 moles of ATP come from?

A) One mole of glucose yields 2 moles of glyceraldehyde 3-phosphate.
B) Two moles of ATP are used during the conversion of glucose to glyceraldehyde 3-phosphate.
C) Glycolysis produces 2 moles of NADH.
D) Fermentation of pyruvate to lactic acid yields 2 moles of ATP.
E) Fermentation of pyruvate to lactic acid yields 2 moles of NAD⁺.

Question 31

In the conversion of pyruvate to acetyl CoA, hydrogen atoms are transferred to NAD⁺.The conversion of pyruvate to acetyl CoA is an example of a(n)

A) endergonic reaction.
B) allosteric reaction.
C) metabolic pathway.
D) reduction reaction.
E) redox reaction.

Question 32

The first and third reactions of the glycolytic pathway result in consumption of ATP.These are examples of

A) endergonic reactions.
B) allosteric reactions.
C) metabolic pathways.
D) oxidation reactions.
E) redox reactions.

Question 33

During the energy-investing portion of glycolysis, the phosphates from ATP molecules are

A) added to carbon atoms to form fructose 1,6-bisphosphate.
B) added to carbon atoms to form 1,3-bisphosphoglycerate.
C) wasted as an energy investment in glucose.
D) used to make pyruvate from glucose.
E) used to make lactate from glucose.

Question 34

The oxidation of acetyl CoA to CO₂ occurs via

A) fermentation.
B) the citric acid cycle.
C) glycolysis.
D) oxidative phosphorylation.
E) the respiratory chain.

Question 35

Absence of _______ would disrupt the citric acid cycle but not glycolysis.

A) ADP
B) NAD⁺
C) FAD
D) CO₂
E) ATP

Question 36

Which product of glycolysis is transported across the mitochondrial membrane, where it is converted to the molecule that enters the citric acid cycle?

A) Glucose
B) Pyruvate
C) Acetyl CoA
D) NADH + H⁺
E) ATP synthase

Question 37

For glycolysis to continue, cells require

A) a respiratory chain.
B) O₂.
C) mitochondria.
D) chloroplasts.
E) NAD⁺.

Question 38

The pyruvate dehydrogenase complex, a multienzyme complex in the citric acid cycle, is located in the

A) thylakoids.
B) cytoplasm.
C) chloroplasts.
D) mitochondrial matrix.
E) cell membrane.

Question 39

Overall, four molecules of ATP are produced during glycolysis.However, at the end of glycolysis there are two ATP molecules, two pyruvate molecules, and two NADH molecules present.The ATP numbers do not match because

A) glucose metabolism is inefficient.
B) glucose phosphate is formed from fructose phosphate.
C) glucose is degraded to CO₂.
D) two ATP are invested in the process of glycolysis.
E) two ATP are used to produce NADH.

Question 40

The citric acid cycle produces

A) ethanol.
B) pyruvate.
C) H₂O.
D) lactic acid.
E) NADH and FADH₂.

Question 41

Rotenone is a potent inhibitor of mitochondrial complex I.If you were to treat isolated mitochondria with rotenone, what would happen to ATP production by oxidative phosphorylation?

A) ATP production would decrease, and electron transport would increase.
B) ATP production would increase, and electron transport would decrease.
C) ATP production and electron transport would decrease.
D) ATP production and electron transport would increase.
E) ATP production would become uncoupled from electron transport.

Question 42

Arsenate is used by phosphate-requiring enzymes as an alternative substrate to phosphate.Arsenate poisoning would have the greatest effect on cellular respiration by inhibiting which enzyme?

A) ATP synthase
B) NADH dehydrogenase
C) Phosphofructokinase
D) Pyruvate decarboxylase
E) Citrate synthase

Question 43

Which analogy best describes the mechanism of ATP synthase?

A) A ball bouncing down a stairway bumps into a cart and causes it to roll forward.
B) Water flowing across a waterwheel makes the wheel turn, which causes a milling grindstone to turn.
C) A rubber band stores more and more potential energy as it is continually twisted in one direction.
D) A snowball pushed down a hill becomes larger and larger as it picks up snow as it rolls.
E) A bucket of water positioned on top of a half-opened door spills its load as the door is pushed open.

Question 44

The chemiosmotic generation of ATP is driven by

A) osmotic movement of H₂O into an area of high solute concentration.
B) the addition of protons to ADP and phosphate via enzymes.
C) oxidative phosphorylation.
D) the proton-motive force.
E) isocitrate dehydrogenase.

Question 45

Refer to the table below, showing data collected from experiments using purified soybean mitochondria incubated in buffer containing compound X, compound Y, or no additions.Three different assays were performed on each group of mitochondria to determine the rate of oxygen uptake, ATP synthesis, and formation of a hydrogen ion gradient.The results are expressed as a percentage relative to the control group. Which conclusion is consistent with these results?

A) Compound X and compound Y inhibit different proteins in the respiratory chain.
B) Compound X and compound Y both uncouple electron transport from ATP synthesis.
C) Compound X uncouples electron transport from ATP synthesis, and compound Y inhibits a protein in the respiratory chain.
D) Compound X inhibits a protein in the respiratory chain, and compound Y uncouples electron transport from ATP synthesis.
E) Compound X prevents oxygen from functioning as the final electron acceptor, and compound Y inhibits a protein in the respiratory chain.

Question 46

Which statement about the respiratory electron transport chain is true?

A) Electrons are received from NADH only.
B) Electrons are passed from donor to recipient carrier molecules in a series of oxidation-reduction reactions.
C) The terminal electron acceptor is usually H₂O.
D) Most of the respiratory proteins are in the cytosol.
E) Energy must be added to move electrons from one electron carrier to the next.

Question 47

Refer to the diagram below, showing electron transport and ATP synthesis.When pure reduced cytochrome c is added to isolated mitochondria in a solution containing ADP, P_i, O₂, and antimycin A (a mitochondria complex II inhibitor), the cytochrome c becomes oxidized and ATP is formed. Which sequence represents the probable flow of electrons in this system?

A) NADH-Q reductase $\rightarrow$ cytochrome c $\rightarrow$ complex IV $\rightarrow$ O₂
B) Cytochrome c $\rightarrow$ O₂ $\rightarrow$ complex IV
C) Complex IV $\rightarrow$ cytochrome c $\rightarrow$ O₂
D) Cytochrome c $\rightarrow$ complex IV $\rightarrow$ 0 O₂
E) Cytochrome c $\rightarrow$ NADH-Q reductase $\rightarrow$ complex IV $\rightarrow$ O₂

Question 48

Oxygen is used by

A) glycolysis.
B) the citric acid cycle.
C) the respiratory electron transport chain.
D) substrate-level phosphorylation.
E) ATP synthase.

Question 49

The drug 2,4-dinitrophenol (DNP) destroys the proton gradient across the inner mitochondrial membrane.What would be the effect of incubating isolated mitochondria in a solution of DNP?

A) O₂ would no longer be reduced to H₂O.
B) ATP synthesis would decline.
C) Mitochondria would show a burst of increased ATP synthesis.
D) Glycolysis would stop.
E) Mitochondria would switch from glycolysis to fermentation.

Question 50

The respiratory electron transport chain

A) is located in the mitochondrial matrix.
B) includes only peripheral membrane proteins.
C) always produces ATP.
D) oxidizes reduced coenzymes.
E) operates simultaneously with fermentation.

Question 51

Electron transport within NADH-Q reductase, cytochrome reductase, and cytochrome oxidase can be coupled to proton transport from the mitochondrial matrix to the space between the inner and outer mitochondrial membranes.This is because those protein complexes

A) are in the mitochondrial matrix.
B) span the inner mitochondrial membrane.
C) are in the space between the inner and outer mitochondrial membranes.
D) remain in the cytoplasm.
E) loosely attach to the inner mitochondrial membrane.

Question 52

ATP is produced by which enzymatic complex?

A) NADH-Q
B) Ubiquinone (Q)
C) ATP synthase
D) Succinate dehydrogenase
E) Cytochrome c reductase

Question 53

Some microbes use non-O₂ electron acceptors to complete the electron transport chain.An example of an organism that carries out this type of electron transport is a soil bacterium that takes in nitrate (NO₃⁻) and releases nitrogen gas (N₂).The nitrate functions as a(n)

A) energy source.
B) electron acceptor.
C) source of electrons.
D) fuel molecule.
E) respiratory chain component.

Question 54

Overall, the _______ within each complex of the respiratory chain decreases as electrons move from the first to the last complex.

A) number of proteins
B) efficiency of electron transfer
C) level of entropy
D) standard free energy
E) degree of oxidation

Question 55

The electron transport chain contains four large protein complexes (I, II, III, and IV) plus cytochrome c and ubiquinone.One function of these components is to

A) sequester electrons.
B) ensure the production of H₂O from O₂.
C) regulate the passage of protons through the chain.
D) synthesize ATP.
E) transport protons across the membrane.

Question 56

According to the chemiosmotic theory, the energy for the synthesis of ATP during the flow of electrons down the respiratory chain is provided directly by the

A) hydrolysis of GTP.
B) reduction of NAD⁺.
C) hydrolysis of ATP.
D) reduction of FAD.
E) diffusion of protons.

Question 57

During cellular respiration, H₂O is produced as a result of the

A) combining of CO₂ with protons.
B) conversion of pyruvate to acetyl CoA.
C) degradation of glucose to pyruvate.
D) reduction of O₂ at the end of the electron transport chain.
E) chemiosmosis process.

Question 58

Increasing the body's brown fat could be a weight loss method because brown fat mitochondria waste energy instead of creating usable energy.What is the mechanism for this waste in brown fat?

A) UCP1 in brown fat uncouples the electron transport chain from ATP synthesis.
B) Brown fat bypasses the process of glycolysis.
C) Brown fat is less efficient than white fat and causes shivering.
D) Hydrogen ions leak across the cell's plasma membrane in white fat.
E) Cytochrome reductase activity decreases in brown fat in response to respiration.

Question 59

In the absence of O₂, cells capable of fermentation

A) accumulate glucose.
B) no longer produce ATP.
C) accumulate pyruvate.
D) can oxidize FAD.
E) can oxidize NADH to produce NAD⁺.

Question 60

The oxidizing agent at the end of the electron transport chain is

A) O₂.
B) NAD⁺.
C) ATP.
D) FAD.
E) ubiquinone.

Question 61

Refer to the table below. The table summarizes the products (in moles) of the complete oxidation of 1 mole of glucose and the complete oxidation of 1 mole of lauric acid, a fatty acid.Use this information to determine how energy production will compare when an equivalent amount of carbon dioxide is produced from oxidation events involving these two molecules.

A) The energy production will be equal for equal quantities of CO₂ production by these two molecules.
B) The energy production by lauric acid oxidation will be greater by 10 ATP when the two molecules are fully oxidized to produce equal quantities of CO₂.
C) The energy production by glucose oxidation will be greater by 10 ATP when the two molecules are fully oxidized to produce equal quantities of CO₂.
D) The energy production by lauric acid oxidation will be greater by 14 ATP when the two molecules are fully oxidized to produce equal quantities of CO₂.
E) The energy production by glucose oxidation will be greater by 14 ATP when the two molecules are fully oxidized to produce equal quantities of CO₂.

Question 62

Key events in the rise of multicellularity in living organisms included the increase in _______ in/on Earth's _______ as a result of photosynthesis, and the evolution of _______ that enabled organisms to use _______.

A) dry land; surface; lungs; oxygen
B) water; oceans; gills; oxygen
C) oxygen; atmosphere; cellular respiration; oxygen
D) carbon dioxide; atmosphere; photosynthesis; carbon dioxide
E) prey; ecosystems; primitive brains; fermentation

Question 63

Bacteria that are shifted from an oxygen-rich environment to an anaerobic environment can continue to grow rapidly only if they

A) increase the rate of the citric acid cycle.
B) produce more ATP per mole of glucose during glycolysis.
C) produce ATP during the oxidation of NADH.
D) increase the rate of transport of electrons down the respiratory chain.
E) increase the rate of the glycolytic reactions.

Question 64

Refer to the table below. A student created this table as a study guide for learning the similarities and differences between lactic acid and alcoholic fermentation.Which statement best evaluates the accuracy of the student's efforts?

A) The table is accurate as written.
B) Lactic acid fermentation has different inputs than alcoholic fermentation.
C) NADH is a net output for both types of fermentation and should be listed.
D) Alcoholic fermentation results in less ATP production than lactic acid fermentation.
E) Both types of fermentation differ by two steps.

Question 65

Most ATP produced in aerobic organisms is made

A) by glycolysis.
B) in the citric acid cycle.
C) using ATP synthase.
D) from photosynthesis.
E) by burning fat.

Question 66

The fermentation process in vertebrate muscle cells produces

A) lactic acid.
B) 12 moles of ATP.
C) pyruvic acid.
D) an excessive amount of energy.
E) ethanol.

Question 67

Substrate-level phosphorylation is used to produce ATP in the absence of O₂.This process depends on _______ to regenerate NAD+.

A) glycolysis
B) fermentation
C) chemiosmosis
D) proteolysis
E) pyruvate oxidation

Question 68

The reduction of pyruvate to lactic acid during fermentation allows glycolysis to continue in the absence of O₂ because this reaction

A) produces H₂O.
B) is a kinase reaction.
C) is coupled to the oxidation of NADH to NAD⁺.
D) is coupled to the formation of ATP.
E) is coupled to the reduction of NAD⁺ to NADH.

Question 69

The component of aerobic respiration that produces the most ATP per mole of glucose is

A) the electron transport chain.
B) the citric acid cycle.
C) glycolysis.
D) lactic acid fermentation.
E) alcoholic fermentation.

Question 70

Which path could a carbon atom follow if it began in an amino acid in a protein in some tuna that was eaten by a cat and eventually ended up in a lipid in the cell membrane of one of the cat's muscle cells?

A) Amino acid $\rightarrow$ citric acid cycle $\rightarrow$ acetyl CoA $\rightarrow$ fatty acid $\rightarrow$ triglyceride $\rightarrow$ cell membrane
B) Amino acid $\rightarrow$ acetyl CoA $\rightarrow$ citric acid cycle $\rightarrow$ pyruvate oxidation $\rightarrow$ cell membrane
C) Amino acid $\rightarrow$ pyruvate oxidation $\rightarrow$ gluconeogenesis $\rightarrow$ glucose $\rightarrow$ glycerol $\rightarrow$ triglyceride $\rightarrow$ cell membrane
D) Amino acid $\rightarrow$ electron transport $\rightarrow$ citric acid cycle $\rightarrow$ acetyl CoA $\rightarrow$ lipid $\rightarrow$ cell membrane
E) Amino acid $\rightarrow$ citric acid cycle $\rightarrow$ acetyl CoA $\rightarrow$ pyruvate $\rightarrow$ glycolysis $\rightarrow$ glycerol $\rightarrow$ triglyceride $\rightarrow$ cell membrane

Question 71

The formation of ethanol from pyruvate is an example of

A) an irreversible reaction.
B) a fermentation process that takes place in the absence of O₂.
C) the production of extra energy from glycolysis.
D) cellular respiration.
E) a high-energy-yielding process.

Question 72

Regardless of the electron or hydrogen acceptor employed, fermentation always produces

A) AMP.
B) DNA.
C) P_i.
D) NAD⁺.
E) CO₂.

Question 73

Before starch can be used for respiratory ATP production, it must be hydrolyzed to

A) pyruvate.
B) fatty acids.
C) amino acids.
D) glucose.
E) oxaloacetate.

Question 74

How many moles of high-energy phosphates are generated in converting 1 mole of glucose to lactate?

A) 1
B) 2
C) 3
D) 4
E) 36

Question 75

When the supply of acetyl CoA being produced exceeds the demands of the citric acid cycle, some of the acetyl CoA is diverted to the synthesis of

A) pyruvate.
B) NAD.
C) proteins.
D) fatty acids.
E) lactic acid.

Question 76

Refer to the table below. The complete oxidation of 1 mole of glucose and the complete oxidation of 1 mole of alanine give the same products in different quantities, as shown in the table.Given this information, it can be stated that

A) alanine produces 6 more ATP per carbon oxidized than glucose.
B) glucose produces 4 more ATP per carbon oxidized than alanine.
C) alanine produces 2 more ATP per carbon oxidized than glucose.
D) glucose produces 1 more ATP per carbon oxidized than alanine.
E) alanine produces approximately the same ATP per carbon oxidized as glucose.

Question 77

Refer to the table below, showing ATP yield from cellular respiration in two different microorganisms.Yield is defined as the net number of molecules of ATP formed for every glucose molecule oxidized. Which statement provides a possible explanation for why the yields differ?

A) There is more opportunity for ATP to hydrolyze spontaneously before it can be used in the eukaryotic cell than in the prokaryotic cell.
B) The prokaryote has fewer respiratory proteins in its electron transport chain than the eukaryote.
C) NADH produced via glycolysis must be shuttled across the mitochondrial membrane in the eukaryote but not in the prokaryote.
D) Some ATP is used in the beginning steps of glycolysis in the eukaryote but not in the prokaryote.
E) The prokaryote has the capability of switching from aerobic to anaerobic respiration whereas the eukaryote does not.

Question 78

Refer to the graph below, showing changes in the source of blood glucose as a person goes from a state of active food intake to a state of starvation. The person's blood glucose levels remain very stable; only the source of glucose changes.Liver cells play an active role in maintaining the stable levels of blood glucose.Which changes in liver cell metabolism could account for the data shown?

A) At 1 hour after eating, liver cells inhibit phosphofructokinase and activate enzymes involved in glycogen breakdown.
B) At 4 hours after eating, liver cells activate enzymes involved in glycogen breakdown as well as enzymes involved in the breakdown of proteins and lipids.
C) At 10 hours after eating, liver cells activate fatty acid synthase and inhibit enzymes involved in the breakdown of proteins and lipids.
D) At 2 days into starvation, liver cells activate phosphofructokinase and inhibit enzymes involved in glycogen breakdown.
E) At 16 days into starvation, liver cells activate phosphofructokinase and inhibit enzymes involved in the breakdown of proteins and lipids.

Question 79

Which process occurs when O₂ is unavailable to a cell?

A) Pyruvate oxidation
B) The citric acid cycle
C) Fermentation
D) Formation of H₂O by the electron transport chain
E) Oxidative phosphorylation

Question 80

In lactate fermentation, NAD⁺ is produced during the

A) oxidation of pyruvate to acetyl CoA.
B) reduction of pyruvate to lactic acid.
C) reduction of acetaldehyde to ethanol.
D) hydrolysis of ATP to ADP.
E) oxidation of glucose.