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The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
A. affinity of oxygen for electrons.
B. transfer of phosphate to ADP.
C. oxidation of glucose and other organic compounds.
D. H+ concentration across the membrane holding ATP synthase.
E. flow of electrons down the electron transport chain.

D

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
A. glycolysis
B. the citric acid cycle
C. the electron transport chain
D. synthesis of acetyl CoA from pyruvate
E. reduction of pyruvate to lactate

A

In mitochondria, exergonic redox reactions
A. are the source of energy driving prokaryotic ATP synthesis.
B. reduce carbon atoms to carbon dioxide.
C. are directly coupled to substrate-level phosphorylation.
D. are coupled via phosphorylated intermediates to ender-gonic processes.
E. provide the energy that establishes the proton gradient.

E

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
A. pyruvate.
B. ADP.
C. oxygen.
D. NAD+.
E. water.

C

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ S Lactate + NAD+
A. NAD+
B. oxygen
C. pyruvate
D. NADH
E. lactate

C

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
A. NAD+ is oxidized.
B. The electrons gain free energy.
C. The cytochromes phosphorylate ADP to form ATP.
D. ATP synthase pumps protons by active transport.
E. The pH of the matrix increases.

E

Most CO2 from catabolism is released during
A electron transport.
B. lactate fermentation.
C. the citric acid cycle.
D. oxidative phosphorylation.
E. glycolysis.

C

Select the correct statement about cellular respiration.
A. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
B. Animals carry out cellular respiration whereas plants carry out photosynthesis.
C. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis.

A

How will a healthy individual's ATP production change during an eight-hour fast?
A. The individual's ATP production will increase significantly.
B. The individual's ATP production will not change significantly.
C. The individual's ATP production will decrease significantly.

B

Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?
A. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
B. The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA.
C. The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2.

A

In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain?
A. The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates.
B. The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.
C. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor.

B

Select all that apply.
A. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.
B. The basic function of fermentation is the production of ethyl alcohol or lactic acid.
C. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis.

A

A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition?
A. His cells contain something that inhibits oxygen use in his mitochondria.
B. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
C. His cells lack the enzyme in glycolysis that forms pyruvate.
D. His cells cannot move NADH from glycolysis into the mitochondria.
E. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

E

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?
A. bioenergetic pathways
B. catabolic pathways
C. fermentation pathways
D. anabolic pathways
E. thermodynamic pathways

B

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction
A. loses electrons and gains potential energy.
B. loses electrons and loses potential energy.
C. gains electrons and loses potential energy.
D. gains electrons and gains potential energy.
E. neither gains nor loses electrons, but gains or loses potential energy.

B

When electrons move closer to a more electronegative atom, what happens?
A. The more electronegative atom is oxidized, and energy is released.
B. The more electronegative atom is reduced, and energy is released.
C. The more electronegative atom is reduced, and entropy decreases.
D. The more electronegative atom is oxidized, and energy is consumed.
E. The more electronegative atom is reduced, and energy is consumed.

B

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 and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide.
B. The oxidation of organic compounds can be used to make ATP.
C. The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds.
D. The covalent bond in O2 is unstable and easily broken by electrons from organic molecules.
E. 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).

E

Which of the following statements describes the results of this reaction?
C6H12O6+ 602--> 6CO2 + 6H20 + Energy
A. CO2 is reduced and is O2 oxidized.
B. C6H12O6 is oxidized and 02 is reduced.
C. C6H12O6 is reduced and CO2 is oxidized.
D. O2 is reduced and CO2 is oxidized.
E. O2 is oxidized and H20 is reduced.

B

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes
A. hydrolyzed.
B. an oxidizing agent.
C. oxidized.
D. reduced.
E. hydrogenated.

C

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes
A. reduced.
B. oxidized.
C. redoxed.
D. dehydrogenated.
E. hydrolyzed.

A

Which of the following statements describes NAD+?
A. NAD+ has more chemical energy than NADH.
B. NAD+ is oxidized by the action of hydrogenases.
C. NAD+ can donate electrons for use in oxidative phosphorylation.
D. In the absence of NAD+, glycolysis can still function.
E. NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.

E

Where does glycolysis take place in eukaryotic cells?
A. mitochondrial intermembrane space
B. mitochondrial inner membrane
C. mitochondrial outer membrane
D. mitochondrial matrix
E. cytosol

E

The ATP made during glycolysis is generated by
A. photophosphorylation.
B. oxidation of NADH to NAD+.
C. substrate-level phosphorylation.
D. electron transport.
E. chemiosmosis.

C

The oxygen consumed during cellular respiration is involved directly in which process or event?
A. glycolysis
B. the citric acid cycle
C. accepting electrons at the end of the electron transport chain
D. the phosphorylation of ADP to form ATP
E. the oxidation of pyruvate to acetyl CoA

C

Which process in eukaryotic cells will proceed normally whether oxygen () is present or absent?
A. oxidative phosphorylation
B. electron transport
C. the citric acid cycle
D. glycolysis
E. chemiosmosis

D

An electron loses potential energy when it
A. shifts to a less electronegative atom.
B. shifts to a more electronegative atom.
C. increases its activity as an oxidizing agent.
D. moves further away from the nucleus of the atom.
E. increases its kinetic energy.

B

Why are carbohydrates and fats considered high energy foods?
A. They can have very long carbon skeletons.
B. They have a lot of electrons associated with hydrogen.
C. They have no nitrogen in their makeup.
D. They have a lot of oxygen atoms.
E. They are easily reduced.

B

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
A. 2%
B. 0%
C. 100%
D. 10%
E. 38%

C

During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is
A. stored in the NADH produced.
B. transferred to ADP, forming ATP.
C. retained in the two pyruvates.
D. used to phosphorylate fructose to form fructose 6-phosphate.
E. transferred directly to ATP.

C

In addition to ATP, what are the end products of glycolysis?
A. CO2and NADH
B. CO2 and pyruvate
C. NADH and pyruvate
D. CO2 and H2O
E. H2O , FADH2, and citrate

C

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

D

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

C

Which kind of metabolic poison would most directly interfere with glycolysis?
A. an agent that closely mimics the structure of glucose but is not metabolized
B. an agent that reacts with NADH and oxidizes it to NAD+
C. an agent that reacts with oxygen and depletes its concentration in the cell
D. an agent that binds to pyruvate and inactivates it
E. an agent that blocks the passage of electrons along the electron transport chain

A

Why is glycolysis described as having an investment phase and a payoff phase?
A. It attaches and detaches phosphate groups.
B. It both splits molecules and assembles molecules.
C. It uses stored ATP and then forms a net increase in ATP.
D. It uses glucose and generates pyruvate.
E. It shifts molecules from cytosol to mitochondrion.

C

Starting with one molecule of glucose, the energy-containing products of glycolysis are
A. 6 CO2, 2 pyruvate, and 30 ATP.
B. 6 CO2, 2 pyruvate, and 2 ATP.
C. 2 NADH, 2 pyruvate, and 2 ATP.
D. 2 FADH2, 2 pyruvate, and 4 ATP.
E. 2 NAD+, 2 pyruvate, and 2 ATP.

C

During cellular respiration, acetyl CoA accumulates in which location?
A. cytosol
B. mitochondrial inner membrane
C. mitochondrial outer membrane
D. mitochondrial intermembrane space
E. mitochondrial matrix

E

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?
A. four
B. six
C. ten
D. eight
E. two

E

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. the citric acid cycle and oxidative phosphorylation
C. fermentation and glycolysis
D. oxidation of pyruvate to acetyl CoA and the citric acid cycle
E. oxidative phosphorylation and fermentation

D

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition?
A. His cells cannot move NADH from glycolysis into the mitochondria.
B. His cells lack the enzyme in glycolysis that forms pyruvate.
C. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
D. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
E. His cells contain something that inhibits oxygen use in his mitochondria.

D

During aerobic respiration, electrons travel downhill in which sequence?
A. food → glycolysis → citric acid cycle → NADH → ATP
B. glucose → ATP → electron transport chain → NADH
C. glucose → pyruvate → ATP → oxygen
D. food → citric acid cycle → ATP → NAD+
E. food → NADH → electron transport chain → oxygen

E

The citric acid cycle
Starting with one molecule of isocitrate and ending with fumarate, how many ATP molecules can be made through substrate-level phosphorylation (see the figure)?
A. 12
B. 11
C. 1
D. 2
E. 24

C

The citric acid cycle.
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 (see the figure)?
A. malate
B. citrate
C. isocitrate
D. succinate
E. α-ketoglutarate

E

The citric acid cycle.
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of are released in the citric acid cycle (see the figure)?
A. 4
B. 3
C. 2
D. 12
E. 6

A

The citric acid cycle.
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the figure?
A. Oxaloacetate will decrease and citric acid will accumulate.
B. Both oxaloacetate and citric acid will decrease.
C. Both oxaloacetate and citric acid will accumulate.
D. There will be no change in the levels of oxaloacetate and citric acid.
E. Oxaloacetate will accumulate and citric acid will decrease.

B

The citric acid cycle.
For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle (see the figure), what is the total number of NADH + FADH2 molecules produced?
A. 5
B. 12
C. 10
D. 4
E. 6

B

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of , (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A.
These three steps result in the formation of
A. acetyl CoA, FAD, , and .
B. acetyl CoA, NAD+, ATP, and .
C. acetyl CoA, FADH2, and .
D. acetyl CoA, , and ATP.
E. acetyl CoA, NADH, , and .

E

What fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle, if glucose is the sole energy source?
A. all of it
B. 1/6
C. 1/2
D. 1/3
E. 2/3

E

In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of , (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A.
How does the addition of coenzyme A, a sulfur-containing molecule derived from a B vitamin, function in the subsequent reaction?
A. It drives the reaction that regenerates NAD+.
B. It utilizes this portion of a B vitamin, which would otherwise be a waste product from another pathway.
C. It provides a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle.
D. It removes one molecule of CO2.
E. It provides the sulfur needed for the molecule to enter the mitochondrion.

C

How does the pyruvate produced by glycolysis enter the mitochondrion?
A. facilitated diffusion
B. through a channel
C. through a pore
D. diffusion
E. active transport

E

Which one of the following is formed by the removal of a carbon (as ) from a molecule of pyruvate?
A. citrate
B. oxaloacetate
C. glyceraldehyde-3-phosphate
D. lactate
E. acetyl CoA

E

Where are the proteins of the electron transport chain located?
A. mitochondrial outer membrane
B. mitochondrial inner membrane
C. mitochondrial matrix
D. cytosol
E. mitochondrial intermembrane space

B

In cellular respiration, the energy for most ATP synthesis is supplied by
A. converting oxygen to ATP.
B. transferring electrons from organic mOlecules to pyruvate.
C. generating carbon dioxide and oxygen in the electron transport chain.
D. a proton gradient across a membrane.
E. high energy phosphate bonds in organic molecules.

D

During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
A. NAD+
B. ADP +P i
C. FADH2
D. ATP
E. NADH

C

The primary role of oxygen in cellular respiration is to
A. yield energy in the form of ATP as it is passed down the respiratory chain.
B. catalyze the reactions of glycolysis.
C. combine with lactate, forming pyruvate.
D. act as an acceptor for electrons and hydrogen, forming water.
E. combine with carbon, forming .

D

Inside an active mitochondrion, most electrons follow which pathway?
A. citric acid cycle → NADH → electron transport chain → oxygen
B. glycolysis → NADH → oxidative phosphorylation → ATP → oxygen
C. citric acid cycle → FADH2 → electron transport chain → ATP
D. pyruvate → citric acid cycle → ATP → NADH → oxygen
E. electron transport chain → citric acid cycle → ATP → oxygen

A

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?
A. glucose
B. carbon dioxide
C. pyruvate
D. lactate
E. molecular oxygen

E

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
A. mitochondrial matrix
B. mitochondrial intermembrane space
C. mitochondrial outer membrane
D. mitochondrial inner membrane
E. cytosol

B

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is
A. oxidation of glucose to and water.
B. the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.
C. the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers.
D. the proton-motive force across the inner mitochondrial membrane.
E. the final transfer of electrons to oxygen.

D

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the
A. reduction of NAD+.
B. lowering of pH in the mitochondrial matrix.
C. restoration of the NA+ /K+ balance across the membrane.
D. formation of ATP.
E. creation of a proton-motive force.

E

Where is ATP synthase located in the mitochondrion?
A. outer membrane
B. electron transport chain
C. mitochondrial matrix
D. cytosol
E. inner membrane

E

It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of the following processes might still be carried on by this isolated inner membrane?
A. the citric acid cycle
B. both the citric acid cycle and oxidative phosphorylation
C. reduction of NAD+
D. glycolysis and fermentation
E. oxidative phosphorylation

E

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
A. citric acid cycle
B. glycolysis
C. oxidation of pyruvate to acetyl CoA
D. oxidative phosphorylation (chemiosmosis)
E. fermentation

D

Approximately how many molecules of ATP are produced from the complete oxidation of two molecules of glucose (C6H12O6) in aerobic cellular respiration?
A. 30-32
B. 4
C. 15
D. 2
E. 60-64

E

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of
A. a reaction with a positive ΔG .
B. osmosis.
C. allosteric regulation.
D. an endergonic reaction coupled to an exergonic process.
E. active transport.

D

Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in
A. only eukaryotic cells, in the presence of oxygen.
B. all cells, in the absence of respiration.
C. all cells, but only in the presence of oxygen.
D. all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.
E. only in mitochondria, using either oxygen or other electron acceptors.

D

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
A. It increases the surface for substrate-level phosphorylation.
B. It allows for an increased rate of glycolysis.
C. It allows for an increased rate of the citric acid cycle.
D. It allows the liver cell to have fewer mitochondria.
E. It increases the surface for oxidative phosphorylation.

E

Brown fat cells produce a protein called thermogenin in their mitochondrial inner membrane. Thermogenin is a channel for facilitated transport of protons across the membrane. What will occur in the brown fat cells when they produce thermogenin?
A. ATP synthesis will decrease, and heat generation will increase.
B. ATP synthesis and heat generation will both increase.
C. ATP synthesis and heat generation will both decrease.
D. ATP synthesis will increase, and heat generation will decrease.
E. ATP synthesis and heat generation will stay the same.

A

In prokaryotes, the respiratory electron transport chain is located
A. in the mitochondrial outer membrane.
B. in the plasma membrane.
C. in the mitochondrial inner membrane.
D. in the bacterial outer membrane.
E. in the cytoplasm.

B

Which catabolic processes may have been used by cells on ancient Earth before free oxygen became available?
A. glycolysis, pyruvate oxidation, and the citric acid cycle
B. glycolysis and the citric acid cycle only
C. glycolysis and fermentation only
D. glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron acceptor other than oxygen
E. oxidative phosphorylation only

D

The figure shows the electron transport chain. Which of the following is the combination of substances that is initially added to the chain?
A. oxygen and protons
B. NAD+, FAD, and electrons
C. NADH, FADH2, and protons
D. oxygen, carbon dioxide, and water
E. NADH, FADH2, and

E

Which of the following most accurately describes what is happening along the electron transport chain in the figure?
A. Chemiosmosis is coupled with electron transfer.
B. Energy of the electrons increases at each step.
C. Molecules in the chain give up some of their potential energy.
D. ATP is generated at each step.
E. Each electron carrier alternates between being reduced and being oxidized.

E

Which of the following most accurately describes what is happening along the electron transport chain in the figure?
A. Chemiosmosis is coupled with electron transfer.
B. Energy of the electrons increases at each step.
C. Molecules in the chain give up some of their potential energy.
D. ATP is generated at each step.
E. Each electron carrier alternates between being reduced and being oxidized.

C

In chemiosmosis, what is the most direct source of energy that is used to convert ADP + ADP +Pi to ATP?
A. energy released from dehydration synthesis reactions
B. energy released from movement of protons through ATP synthase, down their electrochemical gradient
C. energy released as electrons flow through the electron transport system
D. No external source of energy is required because the reaction is exergonic.
E. energy released from substrate-level phosphorylation

B

If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
A. 26
B. 12
C. 14
D. 0
E. 1

C

What is proton-motive force?
A. the force that moves hydrogen to NAD+
B. the force provided by a transmembrane hydrogen ion gradient
C. the force that moves hydrogen into the intermembrane space
D. the force that moves hydrogen into the mitochondrion
E. the force required to remove an electron from hydrogen

B

In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then
A. ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.
B. ATP synthase will stop working.
C. ATP synthase will hydrolyze ATP and pump protons into the matrix.
D. ATP synthase will increase the rate of ATP synthesis.

A

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP.
After the disruption, when electron transfer and ATP synthesis still occur, what must be present?
A. all of the electron transport system and the ability to add CoA to acetyl groups
B. the ATP synthase system
C. plasma membranes like those bacteria use for respiration
D. the electron transport system
E. all of the electron transport proteins as well as ATP synthase

E

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP.
These inside-out membrane vesicles
A. will reverse electron flow to generate NADH from NAD+ in the absence of oxygen.
B. will become alkaline inside the vesicles when NADH is added.
C. will make ATP from ADP and i if transferred to a pH 4 buffered solution after incubation in a pH 7 buffered solution.
D. will hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior.
E. will become acidic inside the vesicles when NADH is added.

E

Which of the following normally occurs regardless of whether or not oxygen is present?
A. glycolysis
B. oxidative phosphorylation (chemiosmosis)
C. oxidation of pyruvate to acetyl CoA
D. fermentation
E. citric acid cycle

A

Which of the following occurs in the cytosol of a eukaryotic cell?
A. glycolysis and fermentation
B. citric acid cycle
C. fermentation and chemiosmosis
D. oxidative phosphorylation
E. oxidation of pyruvate to acetyl CoA

A

The ATP made during fermentation is generated by which of the following?
A. chemiosmosis
B. substrate-level phosphorylation
C. aerobic respiration
D. oxidative phosphorylation
E. the electron transport chain

B

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of
A. ATP, CO2, and lactate.
B. ATP, pyruvate, and oxygen.
C. ATP, pyruvate, and acetyl CoA.
D. ATP, NADH, and pyruvate.
E. ATP, CO2, and ethanol (ethyl alcohol)

E

In alcohol fermentation, NAD+ is regenerated from NADH by
A. reduction of pyruvate to form lactate.
B. reduction of acetaldehyde to ethanol (ethyl alcohol).
C. oxidation of pyruvate to acetyl CoA.
D. oxidation of ethanol to acetyl CoA.
E. reduction of ethanol to pyruvate.

B

One 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. do none of the above.

C

An organism is discovered that thrives both in the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism
E. must use a molecule other than oxygen to accept electrons from the electron transport chain.
A. is a normal eukaryotic organism.
B. is photosynthetic.
C. is an anaerobic organism.
D. is a facultative anaerobe.

D

Which statement best supports the hypothesis that glycolysis is an ancient metabolic pathway that originated before the last universal common ancestor of life on Earth?
A. Glycolysis is found in all eukaryotic cells.
B. Ancient prokaryotic cells, the most primitive of cells, made extensive use of glycolysis long before oxygen was present in Earth's atmosphere.
C. Glycolysis neither uses nor needs .
D. Glycolysis is widespread and is found in the domains Bacteria, Archaea, and Eukarya.
E. The enzymes of glycolysis are found in the cytosol rather than in a membrane-enclosed organelle.

D

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
A. It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
B. It produces much less ATP than does oxidative phosphorylation.
C. It is found in prokaryotic cells but not in eukaryotic cells.
D. It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
E. It relies on chemiosmosis, which is a metabolic mechanism present only in the first cells' prokaryotic cells.

D

When an individual is exercising heavily and when the muscle becomes oxygen-deprived, muscle cells convert pyruvate to lactate. What happens to the lactate in skeletal muscle cells?
A. It is taken to the liver and converted back to pyruvate.
B. It produces and water.
C. It is converted to NAD+.
D. It is converted to alcohol.
E. It reduces FADH2 to FAD+.

A

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells?
A. The mutant yeast will be unable to grow anaerobically.
B. The mutant yeast will be unable to metabolize glucose.
C. The mutant yeast will metabolize only fatty acids.
D. The mutant yeast will die because they cannot regenerate NAD+ from NAD.
E. The mutant yeast will grow anaerobically only when given glucose.

A

You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body?
A. It was released CO2 as and H20 .
B. It was converted to heat and then released.
C. It was broken down to amino acids and eliminated from the body.
D. It was converted to ATP, which weighs much less than fat.
E. It was converted to urine and eliminated from the body.

A

Phosphofructokinase is an important control enzyme in the regulation of cellular respiration. Which of the following statements correctly describes phosphofructokinase activity?
A. It catalyzes the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate, an early step of glycolysis.
B. It is activated by ATP.
C. It is activated by citrate, an intermediate of the citric acid cycle.
D. It is an allosteric enzyme.
E. It is inhibited by AMP.

D

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to
A. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle.
B. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
C. activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle.
D. activate the enzyme and increase the rates of glycolysis and the citric acid cycle.
E. inhibit the enzyme and thus increase the rate of glycolysis and the concentration of citrate.

B

In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue?
A. to increase the production of ATP
B. to increase the rate of oxidative phosphorylation from its few mitochondria
C. to allow the animals to regulate their metabolic rate when it is especially hot
D. to allow other membranes of the cell to perform mitochondrial functions
E. to regulate temperature by converting most of the energy from NADH oxidation to heat

E

What is the purpose of beta oxidation in respiration?
A. oxidation of glucose
B. control of ATP accumulation
C. oxidation of pyruvate
D. feedback regulation
E. breakdown of fatty acids

E

Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
A. glucose, proteins, and fatty acids
B. fatty acids
C. proteins
D. glucose
E. Such yeast cells will not be capable of catabolizing any food molecules, and will therefore die.

D

During intense exercise, as skeletal muscle cells switch to fermentation, the human body will increase its catabolism of
A. carbohydrates only.
B. proteins only.
C. fats, carbohydrates, and proteins.
D. fats and proteins only.
E. fats only.

A

Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur?
A. in all cells all the time
B. in photosynthesizing cells in the light and in other tissues in the dark
C. in cells that are storing glucose only
D. in photosynthetic cells in the light, while photosynthesis occurs concurrently
E. in nonphotosynthesizing cells only

A

Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?
A. malate or fumarate
B. α-ketoglutarate
C. acetyl CoA
D. succinyl CoA
E. pyruvate

C

What carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?
A. either ethanol or lactic acid
B. ethanol
C. glucose
D. pyruvate
E. lactic acid

C

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