Campbell’s Biology, 9e (Reece et al.)
Chapter 9 Cellular Respiration and Fermentation
This is one of the most challenging chapters for students to master. Many students become overwhelmed
and confused by the complexity of the pathways, with the multitude of intermediate compounds,
enzymes, and processes. The vast majority of the questions in this chapter address central concepts
rather than details of these pathways. Other questions have accompanying figures that provide details for
reference and ask students to interpret or use these models. Overall, the emphases are on the inputs and
outputs of each pathway, the relationships among these pathways, the cellular locations, redox as a
central principle in respiration, and chemiosmosis.
Multiple-Choice Questions
1) 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
2) The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction
reaction
A) gains electrons and gains potential energy.
B) loses electrons and loses potential energy.
C) gains electrons and loses potential energy.
D) loses electrons and gains potential energy.
E) neither gains nor loses electrons, but gains or loses potential energy.
3) When electrons move closer to a more electronegative atom, what happens?
A) The more electronegative atom is reduced, and energy is released.
B) The more electronegative atom is reduced, and energy is consumed.
C) The more electronegative atom is oxidized, and energy is consumed.
D) The more electronegative atom is oxidized, and energy is released.
E) The more electronegative atom is reduced, and entropy decreases.
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4) 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) 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.
5) 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) C6H12O6 is reduced and CO2 is oxidized.
E) O2 is reduced and CO2 is oxidized.
6) When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the
molecule becomes
A) hydrolyzed.
B) hydrogenated.
C) oxidized.
D) reduced.
E) an oxidizing agent.
7) When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a
proton), the molecule becomes
A) dehydrogenated.
B) oxidized.
C) reduced.
D) redoxed.
E) hydrolyzed.
8) Which of the following statements describes NAD+?
A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
B) NAD+ has more chemical energy than NADH.
C) NAD+ is oxidized by the action of hydrogenases.
D) NAD+ can donate electrons for use in oxidative phosphorylation.
E) In the absence of NAD+, glycolysis can still function.
9) Where does glycolysis take place in eukaryotic cells?
A) mitochondrial matrix
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) cytosol
10) The ATP made during glycolysis is generated by
A) substrate-level phosphorylation.
B) electron transport.
C) photophosphorylation.
D) chemiosmosis.
E) oxidation of NADH to NAD+.
11) The oxygen consumed during cellular respiration is involved directly in which process or event?
A) glycolysis
B) accepting electrons at the end of the electron transport chain
C) the citric acid cycle
D) the oxidation of pyruvate to acetyl CoA
E) the phosphorylation of ADP to form ATP
12) Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
A) electron transport
B) glycolysis
C) the citric acid cycle
D) oxidative phosphorylation
E) chemiosmosis
13) An electron loses potential energy when it
A) shifts to a less electronegative atom.
B) shifts to a more electronegative atom.
C) increases its kinetic energy.
D) increases its activity as an oxidizing agent.
E) moves further away from the nucleus of the atom.
14) Why are carbohydrates and fats considered high energy foods?
A) They have a lot of oxygen atoms.
B) They have no nitrogen in their makeup.
C) They can have very long carbon skeletons.
D) They have a lot of electrons associated with hydrogen.
E) They are easily reduced.
15) Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by
the reactions of glycolysis?
A) 0%
B) 2%
C) 10%
D) 38%
E) 100%
16) During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most
of the potential energy contained in glucose is
A) transferred to ADP, forming ATP.
B) transferred directly to ATP.
C) retained in the two pyruvates.
D) stored in the NADH produced.
E) used to phosphorylate fructose to form fructose 6-phosphate.
17) 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
18) 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) 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.
19) Starting with one molecule of glucose, the energy-containing products of glycolysis are
A) 2 NAD+, 2 pyruvate, and 2 ATP.
B) 2 NADH, 2 pyruvate, and 2 ATP.
C) 2 FADH2, 2 pyruvate, and 4 ATP.
D) 6 CO2, 2 ATP, and 2 pyruvate.
E) 6 CO2, 30 ATP, and 2 pyruvate.
20) In glycolysis, for each molecule of glucose oxidized to pyruvate
A) two molecules of ATP are used and two molecules of ATP are produced.
B) two molecules of ATP are used and four molecules of ATP are produced.
C) four molecules of ATP are used and two molecules of ATP are produced.
D) two molecules of ATP are used and six molecules of ATP are produced.
E) six molecules of ATP are used and six molecules of ATP are produced.
21) A molecule that is phosphorylated
A) has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate.
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 an increased chemical potential energy; it is primed to do cellular work.
E) has less energy than before its phosphorylation and therefore less energy for cellular work.
22) Which kind of metabolic poison would most directly interfere with glycolysis?
A) an agent that reacts with oxygen and depletes its concentration in the cell
B) an agent that binds to pyruvate and inactivates it
C) an agent that closely mimics the structure of glucose but is not metabolized
D) an agent that reacts with NADH and oxidizes it to NAD+
E) an agent that blocks the passage of electrons along the electron transport chain
23) Why is glycolysis described as having an investment phase and a payoff phase?
A) It both splits molecules and assembles molecules.
B) It attaches and detaches phosphate groups.
C) It uses glucose and generates pyruvate.
D) It shifts molecules from cytosol to mitochondrion.
E) It uses stored ATP and then forms a net increase in ATP.
24) The transport of pyruvate into mitochondria depends on the proton-motive force across the inner
mitochondrial membrane. How does pyruvate enter the mitochondrion?
A) active transport
B) diffusion
C) facilitated diffusion
D) through a channel
E) through a pore
25) Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part,
by the removal of a carbon (CO2) from one molecule of pyruvate?
A) lactate
B) glyceraldehydes-3-phosphate
C) oxaloacetate
D) acetyl CoA
E) citrate
26) 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
27) How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule
of pyruvate?
A) two
B) four
C) six
D) eight
E) ten
28) 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
29) 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 mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial
membrane.
B) His cells cannot move NADH from glycolysis into the mitochondria.
C) His cells contain something that inhibits oxygen use in his mitochondria.
D) His cells lack the enzyme in glycolysis that forms pyruvate.
E) His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
30) During aerobic respiration, electrons travel downhill in which sequence?
A) food → citric acid cycle → ATP → NAD+
B) food → NADH → electron transport chain → oxygen
C) glucose → pyruvate → ATP → oxygen
D) glucose → ATP → electron transport chain → NADH
E) food → glycolysis → citric acid cycle → NADH → ATP
31) 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) 1/6
B) 1/3
C) 1/2
D) 2/3
E) 100/100
32) 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
33) In cellular respiration, the energy for most ATP synthesis is supplied by
A) high energy phosphate bonds in organic molecules.
B) a proton gradient across a membrane.
C) converting oxygen to ATP.
D) transferring electrons from organic molecules to pyruvate.
E) generating carbon dioxide and oxygen in the electron transport chain.
34) 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 + i
E) FADH2
35) 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) act as an acceptor for electrons and hydrogen, forming water.
C) combine with carbon, forming CO2.
D) combine with lactate, forming pyruvate.
E) catalyze the reactions of glycolysis.
36) 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
37) During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the
water come from?
A) carbon dioxide (CO2)
B) glucose (C6H12O6)
C) molecular oxygen (O2)
D) pyruvate (C3H3O3–)
E) lactate (C3H5O3–)
38) In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert
ADP + i to ATP?
A) energy released as electrons flow through the electron transport system
B) energy released from substrate-level phosphorylation
C) energy released from movement of protons through ATP synthase, against the electrochemical
gradient
D) energy released from movement of protons through ATP synthase, down the electrochemical
gradient
E) No external source of energy is required because the reaction is exergonic.
39) Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic
cells?
A) cytosol
B) mitochondrial outer membrane
C) mitochondrial inner membrane
D) mitochondrial intermembrane space
E) mitochondrial matrix
40) The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in
eukaryotic cells is
A) oxidation of glucose to CO2 and water.
B) the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron
transport carriers.
C) the final transfer of electrons to oxygen.
D) the proton-motive force across the inner mitochondrial membrane.
E) the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle
intermediate molecules of ADP.
41) 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-motive force.
E) lowering of pH in the mitochondrial matrix.
42) Where is ATP synthase located in the mitochondrion?
A) cytosol
B) electron transport chain
C) outer membrane
D) inner membrane
E) mitochondrial matrix
43) It is possible to prepare vesicles from portions of the inner mitochondrial membrane. Which one of
the following processes could still be carried on by this isolated inner membrane?
A) the citric acid cycle
B) oxidative phosphorylation
C) glycolysis and fermentation
D) reduction of NAD+
E) both the citric acid cycle and oxidative phosphorylation
44) How many oxygen molecules (O2) are required each time a molecule of glucose (C6H12O6) is
completely oxidized to carbon dioxide and water via aerobic respiration,?
A) 1
B) 3
C) 6
D) 12
E) 30
45) 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)
46) Approximately how many molecules of ATP are produced from the complete oxidation of two
molecules of glucose (C6H12O6) in aerobic cellular respiration?
A) 2
B) 4
C) 15
D) 30-32
E) 60-64
47) 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) active transport.
B) an endergonic reaction coupled to an exergonic reaction.
C) a reaction with a positive ΔG .
D) osmosis.
E) allosteric regulation.
48) Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in
A) all cells, but only in the presence of oxygen.
B) only eukaryotic cells, in the presence of oxygen.
C) only in mitochondria, using either oxygen or other electron acceptors.
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors.
E) all cells, in the absence of respiration.
49) If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized
by carbon dioxide and water, how many ATP molecules can the cell synthesize for each molecule of
pyruvate oxidized to carbon dioxide and water?
A) 0
B) 1
C) 12
D) 14
E) 15
50) What is proton-motive force?
A) the force required to remove an electron from hydrogen
B) the force exerted on a proton by a transmembrane proton concentration gradient
C) the force that moves hydrogen into the intermembrane space
D) the force that moves hydrogen into the mitochondrion
E) the force that moves hydrogen to NAD+
51) 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 allows for an increased rate of glycolysis.
B) It allows for an increased rate of the citric acid cycle.
C) It increases the surface for oxidative phosphorylation.
D) It increases the surface for substrate-level phosphorylation.
E) It allows the liver cell to have fewer mitochondria.
52) 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 and heat generation will both increase.
B) ATP synthesis will increase, and heat generation will decrease.
C) ATP synthesis will decrease, and heat generation will increase.
D) ATP synthesis and heat generation will both decrease.
E) ATP synthesis and heat generation will stay the same.
53) 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 increase the rate of ATP synthesis.
B) ATP synthase will stop working.
C) ATP synthase will hydrolyze ATP and pump protons into the intermembrane space.
D) ATP synthase will hydrolyze ATP and pump protons into the matrix.
54) In prokaryotes, the respiratory electron transport chain is located
A) in the mitochondrial inner membrane.
B) in the mitochondrial outer membrane.
C) in the plasma membrane.
D) in the cytoplasm.
E) in the bacterial outer membrane.
55) Which catabolic processes may have been used by cells on ancient Earth before free oxygen became
available?
A) glycolysis and fermentation only
B) glycolysis and the citric acid cycle only
C) glycolysis, pyruvate oxidation, and the citric acid cycle
D) oxidative phosphorylation only
E) glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation, using an electron
acceptor other than oxygen
56) Which of the following normally occurs regardless of 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)
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57) Which of the following occurs in the cytosol of a eukaryotic cell?
A) glycolysis and fermentation
B) fermentation and chemiosmosis
C) oxidation of pyruvate to acetyl CoA
D) citric acid cycle
E) oxidative phosphorylation
58) 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
59) 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
60) In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production
of
A) ATP, CO2, and ethanol (ethyl alcohol).
B) ATP, CO2, and lactate.
C) ATP, NADH, and pyruvate.
D) ATP, pyruvate, and oxygen.
E) ATP, pyruvate, and acetyl CoA.
61) In alcohol fermentation, NAD+ is regenerated from NADH by
A) reduction of acetaldehyde to ethanol (ethyl alcohol).
B) oxidation of pyruvate to acetyl CoA.
C) reduction of pyruvate to form lactate.
D) oxidation of ethanol to acetyl CoA.
E) reduction of ethanol to pyruvate.