exam 2 review

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1

how do living organism create macromolecules?

create order locally, but energy transformations generate waste heat, and increase entropy in the universe

2

for living organisms, which of the following is an important consequence of the first law of thermodynamics?

organism ultimately must obtain all of the necessary energy for life from its environment

3

when ATP releases some energy, it also releases inorganic phosphate. what purpose does this serve in the cell?

phosphate may be incorporated into many different molecules

4

all the energy to power life comes from the sun, and photosynthetic organisms are the base of the food chain.

true, because organisms aren’t the only base of the food chain though

5

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

loses electrons and loses potential energy

6

cellular respiration can be best described as…

taking electrons from food and giving them to oxygen to make water, and using the energy released to make ATP

7

when a molecule of NAD+ gains one hydrogen atom (a proton and an electron) and an additional electron, the molecule is ________ and becomes NADH.

reduced

8

what is the seventh reaction of glycolysis?

substrate-level phosphorylation

9

the energetic electron, taken from glucose or a breakdown product of glucose, is stripped of its energy to…

actively transport H+ into the intermembrane space

10

ATP synthase at the inner mitochondrial membrane makes ATP by which method?

facilitated diffusion of H+

11

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

energy released from movement of protons through ATP synthase

12

where did the carbons found throughout the body of a plant originate?

air

13

the light reactions, which involve the very hydrophobic chlorophyll, are located where in the chloroplast?

thylakoid membrane

14

the calvin cycle reactions are located where in the chloroplasts?

stroma

15

plants photosynthesize only in the light. plants respire…

both in the light and dark

16

by matching the absorption spectrum of pigments in chloroplasts with the action spectrum of photosynthesis, it is possible to determine…

which pigments are involved in the light reactions

17

what can happen when a photon of light strikes a pigment, such as chlorophyll a?

photon is absorbed, and the resulting energy propels an electron in the molecule to an elevated outer electron shell where it has more energy potential

18

which of the following correctly identifies the products of photosystems 1 and 2?

1: P700 and NADPH

2: O2 and P680+

19

which of the following sequences correctly represent the flow of electrons during photosynthesis?

H2O, NADPH, calvin cycle

20

how are light reactions and the calvin cycle connected?

light reactions provide ATP and NADPH to the calvin cycle, and the calvin cycle returns ADP, phosphate, and NADP+ to the light reactions

21

succulent plants that are able to thrive in the desert have a specialized type of photosynthesis called CAM. these plants have an adaptation for photosynthesis whereby they…

perform the light reactions of photosynthesis during day light and fix CO2 at night; reduce water loss by keeping their stromata closed during the day

22

which items are provided to you by photosynthesis?

oxygen in your latest breath

starch in the toast

paper in textbook

23

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

catabolic pathways

24

whenever energy is transformed, there is always an increase in the…

entropy of the universe

25

the mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as…

feedback inhibition

26

which of the following statements describes NAD+?

NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle

27

which of the following statements describes NADH?

NADH is oxidized for NAD+ at the electron transport chain and in the fermentation

28

where does glycolysis take place in eukaryotic cells?

cytosol

29

the ATP made during glycolysis is generated by…

substrate-level phosphorylation

30

why are carbohydrates and fats considered high energy foods?

they have a lot of electrons associated with hydrogens

31

the primary role of oxygen in cellular respiration is to…

act as an acceptor for electrons and hydrogen, forming water

32

inside an active mitochondrion, most electrons follow which pathway?

citric acid cycle – NADH – electron transport chain – oxygen

33

energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?

mitochondrial intermembrane space

34

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

glycolysis and fermentation

35

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

energy released from ATP synthase pumping hydrogen ions from the mitochondrial matrix

36

which of the following sequences correctly represents the flow of electrons during photosynthesis?

H2O – NADPH – calvin cycle

37

if photosynthesizing green algae are provided with CO2 synthesized with heavy oxygen, later analysis will show that all but one of the following produced by the algae contain the heavy oxygen label. that is…

O2

38

which of the following are products of the light reactions of photosynthesis that are utilized in the calvin cycle?

ATP and NADPH

39

in the thylakoid membranes, what is the main role of the antenna pigment molecules?

harvest photons and transfer light energy to the reaction-center chlorophyll

40

when oxygen is released as a result of photosynthesis, it is a direct by-product of…

splitting water molecules

41

P680+ is said to be the strongest biological oxidizing agent. why?

this molecule has a stronger attraction for electrons that oxygen, to obtain electrons from water

42

why is ATP an important molecule in metabolism?

it provides energy coupling between exergonic and endergonic reactions

43

which of the following statements regarding enzymes is true?

enzymes increase the rate of a reaction by lowering the activation energy barrier

44

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

it does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms

45

which of the following statements best describes the relationship between photosynthesis and respiration?

photosynthesis stores energy in complex organic molecules, whereas respiration releases it

46

the oxygen atoms in the H2O broken down during photosynthesis end up in…

molecular O2 released during photosynthesis

47

during glycolysis, for each mole of glucose oxidized to pyruvate…

2 moles of ATP are used, and 4 moles of ATP are produced

48

what carbon sources can yeast cells metabolize to make ATP from ADP under anaerobic conditions?

glucose

49

the biomass (dry weigh) of a tree comes primarily from…

CO2

50

in thylakoids, protons travel through ATP synthase from the thylakoid space to the stroma. therefore, the catalytic “knobs” of ATP synthase would be located…

on the outside of the inner membrane facing stroma

51

assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. this damage will have the most direct effect on which of the following processes?

the synthesis of ATP

52

which term most precisely describes the cellular process of breaking down large molecules into smaller ones?

catabolism

53

which of the following are true for anabolic pathways?

they consume energy to build up polymers from monomers

54

which of the following is a statement of the first law of thermodynamics?

energy cannot be created or destroyed

55

living organism increase in complexity as they grow, resulting in a decrease in the entropy of an organism. how does this relate to the second law of thermodynamics?

as a consequence of growing, organisms create more disorder in the environment than the decrease in entropy associated with their growth

56

Which of the following statements is a logical consequence of the second law of thermodynamics?

Every chemical reaction must increase the total entropy of the universe.

57

Which of the following statements is representative of the second law of thermodynamics?

Cells require a constant input of energy to maintain their high level of organization

58

what doesn't occur during the calvin cycle?

release of oxygen

59

Which of the following statements is a correct distinction between autotrophs and heterotrophs?

Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and 
other nutrients that are inorganic.

60

The pH of the inner thylakoid space has been measured, as have the pH of the stroma and of the cytosol of a particular plant cell. Which, if any, relationship would you expect to find?

the pH within the thylakoid is less than that of the stroma

61

P680+ is said to be the strongest biological oxidizing agent. Why?

This molecule results from the transfer of an electron to the primary electron acceptor of photosystem II and strongly attracts another electron.

62

Which statement describes the functioning of photosystem II?

The electron vacancies in P680 are filled by electrons derived from water

63

What is the reducing agent in the following reaction? 
Pyruvate + NADH + H+ → Lactate + NAD+

NADH

64

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

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

65

What is proton-motive force?

the transmembrane proton concentration gradient

66

What must be the difference (if any) between the structure of ATP and the structure of the precursor of the A nucleotide in DNA and RNA?

no difference

67

How can one increase the rate of a chemical reaction?

Add a catalyst

68

Sucrose is a disaccharide, composed of the monosaccharides glucose and fructose. The hydrolysis of sucrose by the enzyme sucrase results in

breaking the bond between glucose and fructose and forming new bonds from the atoms of water.

69

According to the induced fit hypothesis of enzyme catalysis, which of the following is correct?

The binding of the substrate changes the shape of the enzymeʹs active site.

70

The following questions are based on the reaction A + B → C + D

Which of the following terms best describes the reaction?

exergonic

71

When you have a severe fever, what may be a grave consequence if this is not controlled?

change in the folding of enzymes

72

How does a noncompetitive inhibitor decrease the rate of an enzyme reaction?

by changing the shape of a reactant

73

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

energy is released, and the more electronegative atom is reduced

74

Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy

C6H12O6 is oxidized and O2 is reduced

75

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

oxidized

76

A molecule that is phosphorylated

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

77

Which process is most directly driven by light energy?

removal of electrons from chlorophyll molecules

78

How is photosynthesis similar in C4 and CAM plants?

In both cases, rubisco is not used to fix carbon initially

79

In mechanism, photophosphorylation is most similar to

oxidative phosphorylation in cellular respiration.

80

The light reactions of photosynthesis supply the Calvin cycle with

ATP and NADPH

81

If plant gene alterations cause the plants to be deficient in photorespiration, what would most probably occur?

Less ATP would be generated

82

The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?

Each one both minimizes photorespiration and optimizes the Calvin cycle

83

Photorespiration lowers the efficiency of photosynthesis by preventing the formation of A) carbon dioxide molecules

3-phosphoglycerate molecule

84

CAM plants keep stomata closed in daytime, thus reducing loss of water. They can do this because they

fix CO2 into organic acids during the night

85

Why are C4 plants able to photosynthesize with no apparent photorespiration

They use PEP carboxylase to initially fix CO2

86

Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be

to test for liberation of O2 in the light.

87

A plant has a unique photosynthetic pigment. The leaves of this plant appear to be reddish yellow. What wavelengths of visible light are being absorbed by this pigment?

blue and violet

88

What are the products of the light reactions that are subsequently used by the Calvin cycle?

ATP and NADPH

89

Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as __________ is to __________.

exergonic; endergonic

90

Which of the following metabolic processes can occur without a net influx of energy from some other process?

C6H12O6 + 6 O2 → 6 CO2 + 6H2O

91

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

accepting electrons at the end of the electron transport chain

92

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

glycolysis

93

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

retained in the pyruvate

94

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?

1

95

Which of the following couples chemiosmosis to energy storage?

ATP synthase

96

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

ATP, CO2, and ethanol (ethyl alcohol).

97

Assume that the reaction has a △G of -5.6 kcal/mol. Which of the following would be true?

The reaction would result in an increase in entropy (S) and a decrease in the total 
energy content (H) of the system.

98

In order to attach a particular amino acid to the tRNA molecule that will transport it, an enzyme, an aminoacyl-tRNA synthetase, is required, along with ATP. Initially, the enzyme has an active site for ATP and another for the amino acid, but it is not able to attach the tRNA. What must occur in order for the final attachment to occur?

The binding of the first two molecules must cause a 3-dimensional change that opens 
another active site on the enzyme.

99

Competitive inhibitors block the entry of substrate into the active site of an enzyme. On which of the following properties of an active site does this primarily depend?

the ability of an enzyme to form a template for holding and joining molecules

100

Which of the following is likely to lead to an increase in the concentration of ATP in a cell?

an increase in a cellʹs catabolic activity

101

Which of the following statements describes enzyme cooperativity?

A substrate molecule bound to an active site affects the active site of several subunits

102

Which of the following is an example of cooperativity?

a molecule binding at one unit of a tetramer allowing faster binding at each of the other three

103

In the process of carbon fixation, RuBP attaches a CO2 to produce a 6 carbon molecule,

which is then split in two. After phosphorylation and reduction, what more needs to happen in the Calvin cycle?

regeneration of rubsico

104

The sugar that results from three ʺturnsʺ of the Calvin cycle is glyceraldehyde-3-phosphate (G3P). Which of the following is a consequence of this?

The formation of starch in plants involves assembling many G3P molecules, with or 
without further rearrangements.

105

Requires glucose

neither the light reactions nor the Calvin cycle

106

Requires CO2

the Calvin cycle alone

107

Produces three-carbon sugars

the Calvin cycle alone

108

Produces NADPH

light reactions alone

109

Produces NADH

neither the light reactions nor the Calvin cycle

110

Produces molecular oxygen (O2)

light reactions alone

111

Requires ATP

the Calvin cycle alone

112

What is the primary function of the Calvin cycle?

synthesize simple sugars from carbon dioxide

113

Which of the following statements best represents the relationships between the light reactions and the Calvin cycle?

The light reactions provide ATP and NADPH to the Calvin cycle, and the cycle returns ADP, Pi, and NADP+ to the light reactions.

114

Where do the enzymatic reactions of the Calvin cycle take place?

stroma of the chloroplast

115

Which of the following types of reactions would decrease the entropy within a cell?

dehydration

116

The organization of organisms has become increasingly complex with time. This statement

is consistent with the second law of thermodynamics

117

Which of the following is an example of potential rather than kinetic energy?

a food molecule made up of energy-rich macromolecule

118

Which of the following is considered an open system

an organism

119

Which of the following is true of metabolism in its entirety?

Metabolism is a property of organismal life

120

The mathematical expression for the change in free energy of a system is △G =△H-TS. Which of the following is (are) correct?

G is the change in free energy.

121

What is the change in free energy of a system at chemical equilibrium

no net change

122

Which of the following is true for all exergonic reactions?

The reaction proceeds with a net release of free energy.

123

Chemical equilibrium is relatively rare in living cells. Which of the following could be an example of a reaction at chemical equilibrium in a cell?

a chemical reaction in which both the reactants and products are only used in a metabolic pathway that is completely inactive

124

A chemical reaction that has a positive △G is correctly described as

endergonic

125

Which of the following best describes enthalpy (H)?

the heat content of a chemical system

126

Which of the following is most similar in structure to ATP?

an RNA nucleotide

127

What term is used to describe the transfer of free energy from catabolic pathways to anabolic pathways

energy coupling

128

Which of the following statements is true concerning catabolic pathways?

They are usually coupled with anabolic pathways to which they supply energy in the form of ATP.

129

When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?

It is lost to the environment

130

Which of the following statements is (are) true about enzyme-catalyzed reactions?

The reaction is faster than the same reaction in the absence of the enzyme.

131

Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?

competitive inhibition

132

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

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

133

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

creation of a proton gradient.

134

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

glycolysis

135

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

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

136

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?

It is taken to the liver and converted back to pyruvate

137

Cyclic electron flow may be photoprotective (protective to light-induced damage). Which of the following experiments could provide information on this phenomenon?

using mutated organisms that can grow but that cannot carry out cyclic flow of electrons and compare their abilities to photosynthesize in different light intensities

138

Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?

They dissipate excessive light energy

139

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

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).

140

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

NADH and pyruvate

141

Starting with one molecule of glucose, the ʺnetʺ products of glycolysis are

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

142

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

2

143

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

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

144

How does pyruvate enter the mitochondrion

active transport

145

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?

oxaloacetate

146

During cellular respiration, acetyl CoA accumulates in which location

mitochondrial matrix

147

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

10

148

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

oxidation of pyruvate to acetyl CoA and the citric acid cycle

149

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

FADH2

150

Reduction of NADP+ occurs during

photosynthesis

151

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

oxidize NADH to NAD+.

152

Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?

ATP and NADPH

153

What does the chemiosmotic process in chloroplasts involve?

establishment of a proton gradient

154

Reduction of oxygen which forms water occurs during

respiration

155

Most CO2 from catabolism is released during

the citric acid cycle

156

In glycolysis, for each molecule of glucose oxidized to pyruvate

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

157

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?

12

158

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

chemiosmotic phosphorylation

159

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

160

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

6

161

Which of the following is a true distinction between fermentation and cellular respiration?

NADH is oxidized by the electron transport chain in respiration only.

162

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is

oxygen

163

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

glycolysis