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AP Biology/Anatomy > Photosynthesis and Respiration: Chapter 9 and 10 > Flashcards

Photosynthesis and Respiration: Chapter 9 and 10 Flashcards

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1
Q

What is the term for metabolic pathways that release stored energy by breaking down
complex molecules?

A

catabolic pathways

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2
Q

The molecule that functions as the reducing agent (electron donor) in a redox or
oxidation-reduction reaction

A

loses electrons and loses energy.

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3
Q

When electrons move closer to a more electronegative atom, what happens?

A

A and C are correct

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4
Q

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and
water release free energy?

A

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).

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5
Q

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.

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6
Q

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction
reaction, the molecule becomes

A

oxidized.

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7
Q

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom
(not a hydrogen ion) the molecule becomes

A

reduce

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8
Q

Which of the following statements describes NAD+?

A

NAD+ is reduced to NADH during both glycolysis and the citric acid cycle.

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9
Q

Where does glycolysis takes place?

A

cytosol

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10
Q

The ATP made during glycolysis is generated by

A

substrate-level phosphorylation.

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11
Q

The oxygen consumed during cellular respiration is involved directly in which process or
event?

A

accepting electrons at the end of the electron transport chain

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12
Q

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or
absent?

A

glycolysis

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13
Q

An electron loses potential energy when it

A

shifts to a more electronegative atom.

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14
Q

Why are carbohydrates and fats considered high energy foods?

A

They have a lot of electrons associated with hydrogen.

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15
Q

Which step shows a split of one molecule into two smaller molecules?

A

B

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16
Q

In which step is an inorganic phosphate added to the reactant?

A

C

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17
Q

In which reaction does an intermediate pathway become oxidized?

A

C

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18
Q

Which step involves an endergonic reaction?

A

A

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19
Q

Which step consists of a phosphorylation reaction in which ATP is the phosphate source?

A

A

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20
Q

Substrate-level phosphorylation accounts for approximately what percentage of the ATP
formed during glycolysis?

A

100%

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21
Q

During glycolysis, when glucose is catabolized to pyruvate, most of the energy of glucose is

A

retained in the pyruvate.

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22
Q

In addition to ATP, what are the end products of glycolysis?

A

NADH and pyruvate

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23
Q

The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mole and the
free energy for the reduction of NAD+ to NADH is +53 kcal/mole. Why are only two
molecules of NADH formed during glycolysis when it appears that as many as a dozen
could be formed?

A

Most of the free energy available from the oxidation of glucose remains in pyruvate,
one of the products of glycolysis.

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24
Q

Starting with one molecule of glucose, theʺnetʺproducts of glycolysis are

A

2 NADH, 2 H+, 2 pyruvate, 2 ATP, and 2 H2O.

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25
Q

In glycolysis, for each molecule of glucose oxidized to pyruvate

A

2 molecules of ATP are used and 4 molecules of ATP are produced.

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26
Q

A molecule that is phosphorylated

A

has an increased chemical reactivity; it is primed to do cellular work

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27
Q

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

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28
Q

Why is glycolysis described as having an investment phase and a payoff phase?

A

It uses stored ATP and then forms a net increase in ATP

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29
Q

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 CO2, 2) is
oxidized to form a two-carbon compound called acetate, and 3) is bonded to coenzyme A.
29) These three steps result in the formation of

A

acetyl CoA, NADH, H+, and CO2

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30
Q

Why is coenzyme A, a sulfur containing molecule derived from a B vitamin, added?

A

to provide a relatively unstable molecule whose acetyl portion can readily bind to
oxaloacetate

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31
Q

How does pyruvate enter the mitochondrion?

A

active transport

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32
Q

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

acetyl CoA

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33
Q

During cellular respiration, acetyl CoA accumulates in which location?

A

mitochondrial matrix

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34
Q

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one
molecule of pyruvate?

A

2

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35
Q

Starting with one molecule of isocitrate and ending with fumarate, what is the maximum
number of ATP molecules that could be made through substrate-level phosphorylation?

A

1

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36
Q

Carbon skeletons for amino acid biosynthesis are supplied by intermediates of the citric
acid cycle. Which intermediate would supply the carbon skeleton for synthesis of a
five-carbon amino acid?

A

΅-ketoglutarate

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37
Q

How many molecules of carbon dioxide (CO2) would be produced by five turns of the
citric acid cycle?

A

10

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38
Q

How many reduced dinucleotides would be produced with four turns of the citric acid
cycle?

A

4 FADH2 and 12 NADH

39
Q

Starting with citrate, which of the following combinations of products would result from
three turns of the citric acid cycle?

A

3 ATP, 6 CO2, 9 NADH, and 3 FADH2

40
Q 
Carbon dioxide (CO2) is released during which of the following stages of cellular
respiration?
A

oxidation of pyruvate to acetyl CoA and the citric acid cycle

41
Q

For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle,
what is the total number of NADH + FADH2 molecules produced?

A

12

42
Q

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.

43
Q

Cellular respiration harvests the most chemical energy from which of the following?

A

chemiosmotic phosphorylation

44
Q

During aerobic respiration, electrons travel downhill in which sequence?

A

food → NADH → electron transport chain → oxygen

45
Q

Where are the proteins of the electron transport chain located?

A

mitochondrial inner membrane

46
Q

Which of the following describes the sequence of electron carriers in the electron transport
chain, starting with the least electronegative?

A

FMN, Fe•S, ubiquinone, cytochromes (Cyt)

47
Q

During aerobic respiration, which of the following directly donates electrons to the electron
transport chain at the lowest energy level?

A

FADH2

48
Q

The primary role of oxygen in cellular respiration is to

A

act as an acceptor for electrons and hydrogen, forming water.

49
Q

Inside an active mitochondrion, most electrons follow which pathway?

A

citric acid cycle → NADH → electron transport chain → oxygen

50
Q

During oxidative phosphorylation, H2O is formed. Where does the oxygen for the
synthesis of the water come from?

A

molecular oxygen (O2)

51
Q

In chemiosmotic phosphorylation, what is the most direct source of energy that is used to
convert ADP + Pi to ATP?

A

energy released from movement of protons through ATP synthase

52
Q

Energy released by the electron transport chain is used to pump H+ ions into which
location?

A

mitochondrial intermembrane space

53
Q

The direct energy source that drives ATP synthesis during respiratory oxidative
phosphorylation is

A

the difference in H+ concentrations on opposite sides of the inner mitochondrial
membrane.

54
Q

When hydrogen ions are pumped from the mitochondrial matrix across the inner
membrane and into the intermembrane space, the result is the

A

creation of a proton gradient.

55
Q

Where is ATP synthase located in the mitochondrion?

A

inner membrane

56
Q

It is possible to prepare vesicles from portions of the inner membrane of the mitochondrial
components. Which one of the following processes could still be carried on by this isolated
inner membrane?

A

oxidative phosphorylation

57
Q

Each time a molecule of glucose (C6H12O6) is completely oxidized via aerobic respiration,
how many oxygen molecules (O2) are required?

A

6

58
Q

Which of the following produces the most ATP when glucose (C6H12O6) is completely
oxidized to carbon dioxide (CO2) and water?

A

oxidative phosphorylation (chemiosmosis)

59
Q

Approximately how many molecules of ATP are produced from the complete oxidation of
two molecules of glucose (C6H12O6) in cellular respiration?

A

76

60
Q

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

A

212

61
Q

Approximately what percentage of the energy of glucose (C6H12O6) is transferred to
storage in ATP as a result of the complete oxidation of glucose to CO2 and water in cellular
respiration?

A

40%

62
Q

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

A

30%

63
Q

What is proton-motive force?

A

the transmembrane proton concentration gradient

64
Q

In liver cells, the inner mitochondrial membranes are about 5 X the area of the outer
mitochondrial membranes, and about 17 X that of the cellʹs plasma membrane. What
purpose must this serve?

A

It increases the surface for oxidative phosphoryation.

65
Q

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes.
However, the fragments will resealʺinside out.ʺThese little vesicles that result can still transfer electrons
from NADH to oxygen and synthesize ATP. If the membranes are agitated still further however, the
ability to synthesize ATP is lost.
65) After the first disruption, when electron transfer and ATP synthesize still occur, what must
be present?

A

all of the electron transport proteins as well as ATP synthase

66
Q

After the second agitation of the membrane vesicles, what must be lost from the
membrane?

A

ATP synthase, in whole or in part

67
Q

It should be possible to reconstitute the abilities of the vesicles if which of the following is
added?

A

intact ATP synthase

68
Q

The accompanying figure shows the electron transport chain. Which of the following is the
combination of substances that is initially added to the chain?

A

NADH, FADH2, and electrons

69
Q

Which of the following most accurately describes what is happening along this chain?

A

Each electron carrier alternates between being reduced and being oxidized.

70
Q

The parts of the figure labeled with Roman numerals symbolize what concept?

A

multimeric groups of proteins in 4 complexes

71
Q

What happens at the end of the chain?

A

4 electrons combine with oxygen and protons.

72
Q

Which of the following couples chemiosmosis to energy storage?

A

ATP synthase

73
Q

Which of the following describes ubiquinone?

A

a small hydrophobic coenzyme

74
Q

Which of the following normally occurs whether or not oxygen (O2) is present?

A

glycolysis

75
Q

Which of the following occurs in the cytosol of a eukaryotic cell?

A

glycolysis and fermentation

76
Q

Which metabolic pathway is common to both cellular respiration and fermentation?

A

glycolysis

77
Q

The ATP made during fermentation is generated by which of the following?

A

substrate-level phosphorylation

78
Q

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the
production of

A

ATP, CO2, and ethanol (ethyl alcohol)

79
Q

In alcohol fermentation, NAD+ is regenerated from NADH during which of the following?

A

reduction of acetaldehyde to ethanol (ethyl alcohol)

80
Q

One function of both alcohol fermentation and lactic acid fermentation is to

A

oxidize NADH to NAD+.

81
Q

An organism is discovered that consumes a considerable amount of sugar, yet does not
gain much weight when denied air. Curiously, the consumption of sugar increases as air is
removed from the organismʹs environment, but the organism seems to thrive even in the
absence of air. When returned to normal air, the organism does fine. Which of the following
best describes the organism?

A

It is a facultative anaerobe.

82
Q

Glycolysis is thought to be one of the most ancient of metabolic processes. Which statement
supports this idea?

A

Glycolysis is the most widespread metabolic pathway.

83
Q

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

A

It is found in the cytosol, does not involve oxygen, and is present in most organisms.

84
Q

Muscle cells, when an individual is exercising heavily and when the muscle becomes
oxygen deprived, 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.

85
Q

When muscle cells are oxygen deprived, the heart still pumps. What must the heart cells be
able to do?

A

continue aerobic metabolism when skeletal muscle cannot

86
Q

When muscle cells undergo anaerobic respiration, they become fatigued and painful. This
is now known to be caused by

A

increase in potassium ions

87
Q

You have a friend who lost 7 kg (about 15 pounds) of fat on aʺlow carbʺdiet. How did the
fat leave her body?

A

It was released as CO2 and H2O.

88
Q

Phosphofructokinase is an important control enzyme in the regulation of cellular
respiration. Which of the following statements describes a function of
phosphofructokinase?

A

It is an allosteric enzyme

89
Q

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 ATP in a cell would be expected to

A

inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle.

90
Q

Even though plants carry on photosynthesis, plant cells still use their mitochondria for
oxidation of pyruvate. When and where will this occur?

A

in photosynthesizing cells in dark periods and in other tissues all the time

91
Q

In vertebrate animals, brown fat tissueʹs color is due to abundant mitochondria. White fat
tissue, on the other hand, is specialized for fat storage and contains relatively few
mitochondria. 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 regulate temperature by converting energy from NADH oxidation to heat

92
Q

What is the purpose of beta oxidation in respiration?

A

breakdown of fatty acids

93
Q

Where do the catabolic products of fatty acid breakdown enter into the citric acid cycle?

A

acetyl CoA

AP Biology/Anatomy (9 decks)

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