49. What must be true when electrons are passed between protein complexes?
a.
Electrons are directly passed from one complex to the next by physical contact.
b.
The oxidized electron carrier passes on the electron and becomes reduced.
c.
A proton is translocated to the inner mitochondrial space.
d.
The matrix decreases in pH.
e.
The reduced electron carrier passes on the electron and becomes oxidized.
50. What are the functions of cytochrome c and ubiquinone?
a.
They translocate protons from the matrix to the inner mitochondrial space.
b.
They shuttle electrons between the protein complexes.
c.
They synthesize water from molecular oxygen.
d.
They produce ATP by substrate-level phosphorylation.
e.
They produce ATP by oxidative phosphorylation.
51. Coenzyme Q (also known as ubiquinone or CoQ) is often found in lotions and moisturizers. Given
what you know about its role in cellular respiration, infer what it might be doing in these products.
a.
It helps glycolysis proceed faster in the cytosol of skin cells.
b.
It absorbs dangerous free radicals (loose electrons) that can cause aging.
c.
It decreases the rate of metabolism and slows cellular growth.
d.
It is absorbed and used by cells with a high metabolism.
e.
It causes older cells to spontaneously die and regenerates new cells.
52. The enzyme succinate dehydrogenase is located in the inner mitochondrial membrane and is directly
involved in what two steps of cellular respiration?
a.
glycolysis and pyruvate oxidation
b.
pyruvate oxidation and citric acid cycle
c.
citric acid cycle and electron transfer system
d.
electron transfer system and glycolysis
e.
electron transfer system and fermentation
53. What is directly responsible for pumping protons out of the matrix in the mitochondria?
a.
protein complexes I, II, III, and IV
b.
cytochrome c and ubiquinone
c.
protein complexes I and III
d.
protein complexes I, III, and IV
e.
NADH and FADH2
54. What is the proton-motive force?
a.
the force needed to move protons into the inner mitochondrial space
b.
the amount of energy required to protonate a glucose molecule
c.
the free energy associated with the removal of hydrogen from NADH
d.
the combination of a proton and voltage gradient across the membrane
e.
the synthesis of ATP from a proton gradient
55. What is chemiosmosis?
a.
the synthesis of ATP by ATP synthase, using a proton gradient
b.
the production of NADH and FADH2 in cellular respiration
c.
the buildup of acetate in the cytoplasm in the absence of oxygen
d.
the breakdown of oxygen as it enters the mitochondria
e.
the release of CO2 as glucose is oxidized in cellular respiration
56. What powers ATP synthase directly?
a.
electron transfer
b.
NADH and FADH2
c.
carbohydrate metabolism
d.
proton gradient
e.
protein complexes
57. Where is ATP synthase located in non-photosynthetic eukaryotes?
a.
outer membrane of the cell
b.
nuclear envelope
c.
rough endoplasmic reticulum
d.
matrix of the mitochondria
e.
inner mitochondrial membrane
58. What directly supplies the electrons for the electron transfer system?
a.
ATP and ADP
b.
FADH2 and NADH
c.
pyruvate and acetate
d.
various enzymes
e.
oxygen and water
a.
the basal unit
b.
the headpiece
c.
the stalk
d.
the lollipop
e.
the three catalytic sites
60. Assuming the pH of the matrix was significantly lower than the inner mitochondrial space, how would
the ATP synthase function differently?
a.
It would require an ion to stabilize it.
b.
ATP synthase would no longer function properly.
c.
It would hydrolyze ATP to form ADP.
d.
It would function exactly the same.
e.
The electron transport chain would be uncoupled.
61. What part of the ATP synthase is responsible for catalyzing ATP formation?
a.
the basal unit
b.
the headpiece
c.
the stalk
d.
the lollipop
e.
the electrons
62. A typical eukaryotic cell that has an abundant supply of glucose and O2 will generate a proton gradient
in its mitochondria by _____________ that is used primarily for _____________.
a.
chemiosmosis; substrate-level phophorylation
b.
the electron transport chain; chemiosmosis
c.
the electron transport chain; substrate-level phosphorylation
d.
fermentation; NAD reduction
e.
glycolysis; production of CO2
63. What would happen to protons that reenter the mitochondrial matrix?
a.
They are attached to NAD+ and FAD.
b.
They combine with oxygen to form water.
c.
They synthesize ATP by substrate-level phosphorylation.
d.
They help in the production of CO2.
e.
They regenerate Coenzyme A.
64. Why does NADH produce more energy than FADH2?
a.
FADH2 donates electrons to protein complex III as opposed to complex II.
b.
FADH2 requires more ATP to produce it and gives more energy back.
c.
NADH and FADH2 are synthesized in different steps of cellular respiration.
d.
NADH donates electrons to a higher energy acceptor in the electron transfer chain.
e.
NADH supplies fewer electrons that are of a higher energy state than FADH2.
65. When you consider the contribution of NADH and FADH2, how many of the 32 total ATP molecules
produced in cellular respiration come from the citric acid cycle?
a.
32
b.
28
c.
24
d.
20
e.
16
66. How efficient is cellular respiration in extracting the energy stored in the bonds of glucose?
a.
20 percent
b.
30 percent
c.
40 percent
d.
50 percent
e.
80 percent
67. There are different shuttle systems to get high energy electrons from the NADH in the cytoplasm to
the NADH in the mitochondria. Why is this beneficial?
a.
This allows for 100% efficiency in cellular respiration.
b.
Each step of cellular respiration can happen faster.
c.
It allows for regulation of ATP production by individual cells.
d.
It diverts more electrons to ATP synthase to produce more ATP.
e.
This is actually a detrimental event that the cell must overcome.
68. If it is true that potato plants use uncoupling proteins (UCPs) in a similar way as mammals, one would
expect the following in these plants:
a.
increased amounts of ATP production.
b.
decreased sugar metabolism.
c.
increased internal tissue temperature.
d.
decreased mitochondrial catabolism.
e.
increased cytosolic pH.
69. Why do cells go through fermentation?
a.
to replenish ADP
b.
to replenish NADH
c.
to replenish FAD
d.
to replenish O2
e.
to replenish NAD+
70. In the absence of O2, the partial metabolism of glucose in human muscles produces _________.
a.
acetaldehyde
b.
carbon dioxide
c.
energy
d.
lactic acid
e.
oxygen
71. If a new human metabolic disease is found that only allows electrons to be used from NADH and not
FADH2, what is a probable explanation for the cause of the disease?
a.
a defect in assembly protein genes for complex II of the electron transfer system
b.
enzyme defects in glycolysis and the citric acid cycle
c.
a deficient amount of cytochrome c and coenzyme Q
d.
improper regulation of phosphofructokinase
e.
inability of oxygen to act as a final electron acceptor
72. Alzheimer disease has been shown to be related to_______.
a.
alcoholic fermentation in the brain
d.
decreased brain metabolism
b.
lactate fermentation in the brain
e.
increased mitochondrial enzyme activity
c.
increased brain metabolism
MATCHING
Refer to the illustration above for the following questions. In what part of the mitochondrion or cell are
the following steps of cellular respiration taking place?
a.
outer mitochondrial membrane
b.
intermembrane compartment
c.
cytosol
d.
inner mitrochondrial membrane
e.
matrix
73. glycolysis
74. pyruvate oxidation
75. citric acid cycle
76. electron transfer system
77. ATP synthesis
78. oxidative phosphorylation
OTHER
79. Arrange the following steps of cellular respiration in their proper order. Write the letter of the first step
next to 1 and the letter of the last step next to 5.
A.
pyruvate oxidation
B.
citric acid cycle
C.
electron transfer system
D.
transport of glucose into cell
E.
glycolysis
D
E
A
B
C
SHORT ANSWER
80. In eukaryotes, where do the reactions of cellular respiration occur?
81. Both glycolysis and the citric acid cycle can be regulated by feedback inhibition. Provide two
examples of feedback inhibition.
82. How did Hans Krebs discover the citric acid cycle?
83. How do cyanide and carbon monoxide affect cellular respiration?
84. What is the difference between a strict anaerobe and a facultative anaerobe?
MODIFIED TRUE/FALSE
If the statement is true, answer “T”. If the statement is false, answer “F” and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
85. Metabolism is best described as how fast mitochondria work.
86. Molecular oxygen that is breathed in is expired as carbon dioxide.
87. If during a chemical reaction, a molecule loses hydrogens, it could be described as being oxidized.
88. Both plants and animals possess mitochondria, which are used for cellular respiration to make ATP.
89. Glycolysis takes place in the mitochondria.
90. During glycolysis, ATP is produced by oxidative phosphorylation.
91. During the process of pyruvate oxidation, pyruvate is broken down and the remaining two carbons are
attached to Coenzyme A.
92. During pyruvate oxidation, one molecule of ATP is produced.
93. Two mobile electron carriers that are important for the electron transfer system are cytochrome c and
coenzyme Q.
94. The main purpose of fermentation is to regenerate NADH and FADH2.