Unit 4: HW 13 on Energy Generation

Question 1

Question 1: In this illustration of the structure of ATP synthase, which of the components rotate?

Answer 1

1, 5

Question 2

The drug 2,4-dinitrophenol (DNP) makes the mitochondrial inner membrane permeable to H+. The resulting disruption of the proton gradient inhibits the mitochondrial production of ATP.

What additional effect would DNP have on the transport of ATP out of the mitochondrial matrix?

Choose one:
A. ATP transport will increase because ATP synthase will be forced to operate in the “reverse” direction.
B. None, because the inner membrane is permeable to ATP.
C. None, because ATP export is not coupled to the movement of protons across the inner membrane.
D. ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane.
E. ATP transport will decrease because less ATP will be available to diffuse across the inner membrane.

Answer 2

D. ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane.

Question 3

Investigators introduce two proteins into the membrane of artificial lipid vesicles: (1) an ATP synthase isolated from the mitochondria of cow heart muscle, and (2) a light-activated proton pump purified from the prokaryote Halobacterium halobium. The proteins are oriented as shown in the diagram. When ADP and Pi are added to the external medium and the vesicle is exposed to light, would this system produce ATP?

Choose one:
A. No, because no electron-transport chain is present.
B. Yes, because the proton pump will generate a proton gradient that ATP synthase can use to synthesize ATP.
C. No, because ATP synthase is not oriented correctly.
D. No, because protons are small enough to pass freely in and out of an artificial lipid vesicle.
E. No, because cows and prokaryotes are so distantly related that their proteins cannot be expected to work together.

Answer 3

C. No, because ATP synthase is not oriented correctly.

Question 4

Not all fat cells are equivalent. Humans and other animals contain both white fat cells and brown fat cells, named after their color. Because increases in brown fat cells may aid weight loss, researchers are interested in factors that control the ratio of white fat cells and brown fat cells, as detailed in a 2017 article in Obesity Reviews. What is the mechanism for how brown fat cells aid weight loss?

Choose one:
A. Brown fat cell mitochondria contain an uncoupling protein.
B. Brown fat cells express bacteriorhodopsin.
C. Brown fat cells contain fewer mitochondria than white fat cells.
D. Brown fat cells produce a lot of ATP.

Answer 4

A. Brown fat cell mitochondria contain an uncoupling protein.

Question 5

The proton gradient that drives ATP synthesis during photosynthesis is generated by which of the following?

Choose one:
A. an electron carrier that pumps protons out of the stroma into the thylakoid space
B. the operation of two photosystems that work in series
C. an electron carrier that removes electrons from water
D. an electron carrier that receives electrons from photosystem I
E. an electron carrier that pumps protons out of the thylakoid space into the stroma

Answer 5

A. an electron carrier that pumps protons out of the stroma into the thylakoid space

Question 6

Carbon fixation occurs in the second stage of photosynthesis, during the light-independent reactions of the Calvin cycle. In the first step of this cycle, the enzyme Rubisco adds CO2 to the energy-rich compound ribulose 1,5-bisphosphate, ultimately producing two molecules of 3-phosphoglycerate.

In a culture of green alga that is carrying out photosynthesis in the presence of CO2 in the laboratory, what would happen to the levels of ribulose 1,5-bisphosphate and 3-phosphoglycerate in the minutes after the lights were turned off and the cultures were plunged into darkness?

Choose one:
A. Nothing would happen because the Calvin cycle is not light-dependent.
B. Ribulose 1,5-bisphosphate would accumulate, but 3-phosphoglycerate would be depleted.
C. Both would accumulate.
D. Both would be depleted.
E. Ribulose 1,5-bisphosphate would be depleted, but 3-phosphoglycerate would accumulate.

Answer 6

E. Ribulose 1,5-bisphosphate would be depleted, but 3-phosphoglycerate would accumulate.

Question 7

What happens to the ATP produced during stage 1 of photosynthesis?

Choose one:
A. It is consumed within the chloroplast to produce NADPH.
B. It is consumed within the chloroplast to fuel electron transport.
C. It is exported from the chloroplast and used to produce sucrose.
D. It is consumed within the chloroplast to produce glyceraldehyde 3-phosphate.
E. It is exported from the chloroplast to fuel the plant’s metabolic needs.

Answer 7

D. It is consumed within the chloroplast to produce glyceraldehyde 3-phosphate.

Question 8

What is true of nitrogen fixation?

Choose one:
A. It requires a small energy input and is thus energetically favorable.
B. It promoted the evolution of ancient cells by allowing them to convert N2 to NO2 near thermal vents.
C. It reduces N2 to ammonia (NH3).
D. It converts CO2 and H2O into sugars.
E. It can be used to generate an H+ gradient.

Answer 8

C. It reduces N2 to ammonia (NH3).

Question 9

The buildup of lactic and formic acids generated by anaerobic fermentation likely favored the evolution of which of the following?

Choose one:
	A. cells that could pump protons
	B. cells that could use the energy of sunlight to produce NADPH
	C. hydrothermal vents
	D. eukaryotic cells
	E. multicellular life

Answer 9

A. cells that could pump protons

Question 10

Which activated carrier contains a high-energy bond whose hydrolysis releases a large amount of free energy?

Choose one:
A.  	glucose
B.  	NADH
C.  	ATP
D.  	water
E.  	high-energy electrons

Answer 10

C. ATP

Question 11

Which of the following drives the production of ATP from ADP and Pi by ATP synthase?

Choose one:
	A. sunlight
	B. phosphorylation
	C. a proton (H+) gradient
	D. a sodium (Na+) gradient
	E. hydrolysis

Answer 11

C. a proton (H+) gradient

Question 12

In the electron-transport chain, as electrons move along a series of carriers, they release energy that is used to do what?

Choose one:
	A. pump protons across a membrane
	B. split water into protons and oxygen
	C. hydrolyze ATP
	D. phosphorylate ADP to form ATP
	E. oxidize food molecules

Answer 12

A. pump protons across a membrane

Question 13

What is true of the organelles that produce ATP in eukaryotic animal cells?

Choose one:
A. They contain the same genes as the chloroplasts of plant cells.
B. They reproduce sexually.
C. They have a separate set of DNA that contains many of the same genes found in the nucleus.
D. They evolved from bacteria engulfed by ancestral cells billions of years ago.
E. They harbor eukaryotic-like biosynthetic machinery for making RNA and protein.

Answer 13

D. They evolved from bacteria engulfed by ancestral cells billions of years ago.

Question 14

Which of the following organisms have mitochondria in their cells?

Choose one or more:
	yeasts
	bacteria
	protozoa
	animals
	plants

Answer 14

yeasts
protozoa
animals
plants

Question 15

Approximately how many molecules of ATP can be produced in mitochondria from the complete oxidation of a single glucose molecule?

Choose one:
	2
	4
	1000 to 2000
	30
	It depends on the numbe

Answer 15

30

Question 16

Which of the following statements are true of mitochondria?

Choose one or more:
A. They are similar in size and shape to bacteria.
B. Inside a cell, they are mobile, constantly changing shape and position.
C. They contain their own DNA and RNA.
D. They contain an outer membrane, an inner membrane, and two internal compartments.
E. In plant cells, they are replaced by chloroplasts.

Answer 16

A. They are similar in size and shape to bacteria.
B. Inside a cell, they are mobile, constantly changing shape and position.
C. They contain their own DNA and RNA.
D. They contain an outer membrane, an inner membrane, and two internal compartments.

Question 17

Question 17: Which part of the mitochondrion contains porins?

Answer 17

C

Question 18

Question 18: Which part of the mitochondrion contains the proteins that carry out oxidative phosphorylation?

Answer 18

B

Question 19

Question 19: Which part of the mitochondrion contains the enzymes needed to complete the oxidation of food-derived molecules?

Answer 19

A

Question 20

Question 20: Which part of the mitochondrion contains the same mix of small molecules and inorganic ions as the cytosol?

Answer 20

D

Question 21

In an animal cell, where are the proteins of the electron-transport chain located?

Choose one:
	A. outer mitochondrial membrane
	B. inner mitochondrial membrane
	C. mitochondrial matrix
	D. plasma membrane
	E. ER membrane

Answer 21

B. inner mitochondrial membrane

Question 22

Which of the following are consumed as fuel within mitochondria?

Choose one or more:
A.	glucose
B.	pyruvate 
C.	fatty acids
D.	amino acids
E.	acetyl CoA

Answer 22

B. pyruvate
C. fatty acids
D. amino acids
E. acetyl CoA

Question 23

The electron-transport chain in mitochondria accepts high-energy electrons directly from which molecule?

Choose one:
	A. acetyl CoA
	B. pyruvate
	C. H2O
	D. NADH
	E. ATP

Answer 23

D. NADH

Question 24

Which is true about electrons as they move through the electron-transport chain?

Choose one:
A. Electrons can gain or lose energy, depending on where they enter along the electron-transport chain.
B. Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain.
C. Electrons are pumped across the mitochondrial membrane as they move along the electron-transport chain.
D. Electrons neither gain nor lose energy as they move along the electron-transport chain.
E. Electrons start out at very low energy and gain energy at each transfer step.

Answer 24

B. Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain.

Question 25

The movement of electrons through the electron-transport chain in mitochondria does which of the following?

Choose one:
A. pumps protons out of the mitochondrial matrix
B. consumes ATP
C. produces NADH
D. produces oxygen
E. pumps ATP across the inner mitochondrial membrane

Answer 25

A. pumps protons out of the mitochondrial matrix

Question 26

In mitochondria, what is the final electron acceptor in the electron-transport chain?

Choose one:
	A. water (H2O)
	B. NADH and FADH2
	C. ADP
	D. oxygen (O2)
	E. carbon dioxide (CO2)

Answer 26

D. oxygen (O2)

Question 27

What is true of mobile electron carriers?

Choose one:
A. They pump protons across a membrane.
B. They feed electrons into the electron-transport chain.
C. They ferry electrons between one respiratory complex and the next.
D. They transfer electrons to oxygen to produce water.
E. They accept electrons from NADH.

Answer 27

C. They ferry electrons between one respiratory complex and the next.

Question 28

The electron-transport chain pumps protons in which direction?

Choose one:
A. from the intermembrane space to the matrix
B. from the cytosol to the intermembrane space
C. from the intermembrane space to the cytosol
D. from the matrix to the cytosol
E. from the matrix to the intermembrane space

Answer 28

E. from the matrix to the intermembrane space

Question 29

It is energetically favorable for protons to flow in which direction?

Choose one:
A. from the mitochondrial matrix to the intermembrane space
B. across the outer mitochondrial membrane
C. toward the compartment with the lowest pH
D. toward the compartment with the most positive charge
E. from the intermembrane space to the mitochondrial matrix

Answer 29

E. from the intermembrane space to the mitochondrial matrix

Question 30

Which is true of ATP synthase?

Choose one:
A. It cannot serve as a proton pump.
B. It is not present in plants or bacteria.
C. It can break down ATP but not generate it.
D. It can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.
E. It can generate ATP but not break it down.

Answer 30

D. It can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.

Question 31

When protons move down their electrochemical gradient into the mitochondrial matrix, what do they do?

Choose one:
	A. produce NADH
	B. produce ATP
	C. consume ATP
	D. move electrons through the respiratory chain
	E. produce NAD+

Answer 31

B. produce ATP

Question 32

During oxidative phosphorylation, why does a single molecule of NADH result in the production of more ATP molecules than a single molecule of FADH2?

Choose one:
A. NADH donates more electrons to the electron-transport chain than does FADH2.
B. FADH2 is less likely than NADH to participate in the electron-transport chain.
C. FADH2 has a lower electron affinity than does NADH.
D. FADH2 promotes the pumping of more protons than does NADH.
E. FADH2 and NADH feed their electrons to different carriers in the electron-transport chain.

Answer 32

E. FADH2 and NADH feed their electrons to different carriers in the electron-transport chain.

Question 33

In terms of energy production, what is true of cell respiration?

Choose one:
A. It is more efficient than a gasoline-powered engine.
B. It is equally as efficient as a gasoline-powered engine.
C. It can be used to run a gasoline-powered engine.
D. It cannot be compared to a gasoline-powered engine.
E. It is less efficient than a gasoline-powered engine.

Answer 33

A. It is more efficient than a gasoline-powered engine.

Question 34

Diseases that disrupt the function of mitochondria are particularly harmful to muscle and nerve cells for what reason?

Choose one:
A. These cells lack mitochondria.
B. These cells undergo rapid cycles of cell division to function.
C. These cells need large amounts of ATP to function normally.
D. These cells can produce energy by fermentation.
E. These cells cannot produce energy by fermentation.

Answer 34

C. These cells need large amounts of ATP to function normally.

Question 35

Which activated carriers are produced by the citric acid cycle?

Choose one or more:
	FADH2
	NADH
	CO2
	NADPH
	GTP
	ATP

Answer 35

FADH2
NADH
GTP

Question 36

The electrochemical proton gradient across the mitochondrial membrane can be used to drive which processes?

Choose one or more:
A. export of pyruvate from the mitochondrial matrix
B. import of pyruvate into the mitochondrial matrix
C. export of ATP from the mitochondrial matrix
D. import of ADP into the mitochondrial matrix
E. import of ATP into the mitochondrial matrix

Answer 36

B. import of pyruvate into the mitochondrial matrix
C. export of ATP from the mitochondrial matrix
D. import of ADP into the mitochondrial matrix

Question 37

Which of the following is true of NADH?

Choose one:
A. It has a strong affinity for electrons and a positive redox potential.
B. It has a weak affinity for electrons and a positive redox potential.
C. It donates electrons directly to molecular oxygen.
D. It has a weak affinity for electrons and a negative redox potential.
E. It has a strong affinity for electrons and a negative redox potential.

Answer 37

D. It has a weak affinity for electrons and a negative redox potential.

Question 38

In a test tube, NADH has a strong tendency to do what?

Choose one:
	A. either donate or accept electrons depending on the electrochemical proton gradient
	B. donate electrons to water
	C. accept electrons from O2
	D. accept electrons from water
	E. donate electrons to O2

Answer 38

E. donate electrons to O2

Question 39

Question 35: What could be true of a baby born following mitochondrial replacement therapy, a treatment designed to prevent the transmission of mitochondrial defects?

Choose one:
A. The baby would die shortly after birth.
B. The baby would have genetic material from three “parents” in each cell.
C. The baby would have two nuclei in each cell.
D. The baby would have mitochondria from both mother and father in each cell.
E. The baby would have mitochondria from three different “parents” in each cell.

Answer 39

B. The baby would have genetic material from three “parents” in each cell.

Question 40

During electron transport, which serves as a ready source for protons that can be pumped across the membrane?

Choose one:
	A. ATP
	B. NADH
	C. glucose
	D. O2
	E. H2O

Answer 40

E. H2O

Question 41

Why does cytochrome c oxidase bind to oxygen very tightly?

Choose one:
A. Oxygen is too scarce.
B. The complex contains multiple iron–sulfur clusters.
C. Cyanide prevents oxygen from dissociating.
D. Oxygen has a very low affinity for electrons.
E. Release of partially reduced oxygen radicals can damage the cell.

Answer 41

E. Release of partially reduced oxygen radicals can damage the cell.

Question 42

When the difference in redox potential between two molecules is highly positive, what is true of the transfer of electrons between them?

Choose one:
	A. It is accompanied by a rise in ΔG.
	B. It requires an input of energy.
	C. It is highly favorable.
	D. It produces ATP.
	E. It is highly unfavorable.

Answer 42

C. It is highly favorable.

Question 43

Most of the energy for the synthesis of ATP comes from which molecule?

Choose one:
A. FADH2 produced by the citric acid cycle
B. NADH produced by glycolysis
C. NADH produced by the conversion of pyruvate to acetyl CoA
D. NADH produced by the citric acid cycle
E. GTP produced by the citric acid cycle

Answer 43

D. NADH produced by the citric acid cycle

Question 44

How do specialized brown fat cells take advantage of oxidative phosphorylation to generate heat?

Choose one:
A. They contain a carrier protein that dissipates the proton gradient across the inner mitochondrial membrane.
B. They contain a carrier protein that produces a larger proton gradient across the inner mitochondrial membrane.
C. They produce and consume larger than normal amounts of ATP.
D. They oxidize only sugars, and store all their fat.
E. They have the ability to carry out photosynthesis.

Answer 44

A. They contain a carrier protein that dissipates the proton gradient across the inner mitochondrial membrane.

Question 45

Stage 1 of photosynthesis is, in large part, equivalent to what process?

Choose one:
	A. glycolysis
	B. the production of acetyl CoA by the pyruvate dehydrogenase complex
	C. the carbon-fixation cycle
	D. oxidative phosphorylation
	E. the citric acid cycle

Answer 45

D. oxidative phosphorylation

Question 46

In the electron-transport chain in chloroplasts, which molecule serves as the final electron acceptor?

Choose one:
	ADP
	NAD+
	H2O
	NADP+
	O2

Answer 46

NADP+

Question 47

Which of these is able to boost electrons to the very high energy level needed to make NADPH from NADP+?

Choose one:
	A. photosystem II
	B. cytochrome b6-f complex
	C. ATP synthase
	D. H2O
	E. photosystem I

Answer 47

E. photosystem I

Question 48

What serves as the final electron acceptor in the photosynthetic electron-transport chain that carries electrons from photosystem II?

Choose one:
	A. H2O
	B. photosystem I
	C. O2
	D. cytochrome b6-f complex
	E. CO2

Answer 48

B. photosystem I

Question 49

In photosynthesis, what drives the generation of ATP by ATP synthase?

Choose one:
A. the transfer of high-energy electrons to ATP synthase
B. the phosphorylation of ATP synthase
C. a proton gradient across the thylakoid membrane
D. the absorption of light by a photosynthetic reaction center
E. the generation of a charge separation in the photosynthetic reaction center

Answer 49

C. a proton gradient across the thylakoid membrane

Question 50

Which photosystem is depicted in this simplified diagram?

(Question 50)

Choose one:
	photosystem II
	photosystem I
	More information is needed to determine which photosystem is depicted.
	either photosystem I or II

Answer 50

photosystem II

Question 51

Which photosystem is depicted in this simplified diagram?

(Question 51)

Choose one:
	photosystem II
	photosystem I
	More information is needed to determine which photosystem is depicted.
	either photosystem I or II

Answer 51

photosystem I

Question 52

How does the photosynthetic machinery produce enough energy to transfer electrons from H2O to NADPH?

Choose one:
A. The proton gradient produced by electron transport powers the production of NADPH.
B. Two photosystems operating in series couple their electron-energizing steps.
C. Two photosystems operating in series generate enough light energy to produce NADPH.
D. The proton gradient produced by electron transport lowers the redox potential of H2O.
E. ATP produced by photosystem II powers the synthesis of NADPH.

Answer 52

B. Two photosystems operating in series couple their electron-energizing steps.

Question 53

When an electron is removed from the reaction center of photosystem II, the missing electron is replaced by an electron from which of the following?

Choose one:
	A. sunlight
	B. H+
	C. photosystem I
	D. H2O
	E. manganese

Answer 53

D. H2O

Question 54

During photosynthesis, what happens in the water-splitting step?

Choose one:
A. It generates essentially all of the O2 in the Earth’s atmosphere.
B. It takes place during stage 2 of photosynthesis.
C. It consumes protons and thereby depletes the proton gradient across the thylakoid membrane.
D. It occurs on the stromal side of the thylakoid membrane.
E. It is catalyzed by an enzyme containing an iron–sulfur cluster.

Answer 54

A. It generates essentially all of the O2 in the Earth’s atmosphere.

Question 55

Which photosystem is depicted in this simplified diagram?

(Question 55)

Choose one:
	More information is needed to determine which photosystem is depicted.
	photosystem II
	either photosystem I or II
	photosystem I

Answer 55

photosystem II

Question 56

What is true of the process of combining CO2 and H2O to make a carbohydrate?

Choose one:
A. It produces ATP.
B. It is energetically favorable.
C. It is energetically unfavorable.
D. It takes place in all eukaryotic cells.
E. It occurs only during daylight hours.

Answer 56

C. It is energetically unfavorable.

Question 57

What provides the fuel to convert CO2 into sugars in chloroplasts?

Choose one:
A. ATP and NADPH generated in the photosynthetic light reactions
B. Nothing; the reactions do not require energy.
C. ATP generated by cell respiration
D. oxidation of food molecules
E. a proton gradient across a membrane

Answer 57

A. ATP and NADPH generated in the photosynthetic light reactions

Question 58

For every three molecules of CO2 that enter the carbon-fixation cycle, what is produced and what is consumed?

Choose one:
A. 1 molecule of glyceraldehyde 3-phosphate is produced, and 9 molecules of ATP + 6 molecules of NADPH are consumed.
B. 1 molecule of glyceraldehyde 3-phosphate is produced, and 6 molecules of ATP + 9 molecules of NADPH are consumed.
C. 3 molecules of glyceraldehyde 3-phosphate are produced, and 9 molecules of ATP + 6 molecules of NADPH are consumed.
D. 1 molecule of glyceraldehyde 3-phosphate is produced, and 9 molecules of ATP + 12 molecules of NADPH are consumed.
E. 6 molecules of glyceraldehyde 3-phosphate are produced, and 6 molecules of ATP + 9 molecules of NADPH are consumed.

Answer 58

A. 1 molecule of glyceraldehyde 3-phosphate is produced, and 9 molecules of ATP + 6 molecules of NADPH are consumed.

Question 59

n this simplified diagram of the reactions of the carbon-fixation cycle, which step is catalyzed by the enzyme Rubisco?

(Question 59)

Choose one:
	A
	B
	C
	D
	E

Answer 59

E

Question 60

During very active periods of photosynthesis, the glyceraldehyde 3-phosphate generated by carbon fixation in the chloroplast stroma is stored as which molecule?

Choose one:
	pyruvate
	glycogen
	starch
	ATP
	CO2

Answer 60

Starch

Question 61

What is true of the antenna complex of a photosystem?

Choose one:
A. It converts light energy into chemical energy.
B. It extracts electrons from water.
C. It includes a special pair of chlorophylls.
D. It captures light energy.
E. It passes electrons to a photosynthetic electron transport chain.

Answer 61

D. It captures light energy.

Question 62

What is true of stage 2 of photosynthesis?

Choose one:
A. It produces all of the O2 we breathe.
B. It produces glyceraldehyde 3-phosphate in the stroma.
C. It begins with the production of ATP and NADPH and ends with their consumption.
D. It takes place in the chloroplast grana.
E. It generates a proton gradient across the thylakoid membrane.

Answer 62

B. It produces glyceraldehyde 3-phosphate in the stroma.

Question 63

What is one reason that plants do not generally produce sugars after dark?

Choose one:
A. The enzymes involved in stage 2 of photosynthesis are inactivated in the dark.
B. CO2 is unavailable after dark.
C. O2 is unavailable after dark.
D. The enzymes involved in stage 1 of photosynthesis are inactivated in the dark.
E. The enzymes involved in stage 2 of photosynthesis are inactivated in the light.

Answer 63

A. The enzymes involved in stage 2 of photosynthesis are inactivated in the dark.

Question 64

Photosynthesis allows plants to capture energy from sunlight to produce what?

Choose one:
	sugars
	H2O
	chlorophyll
	NADH
	CO2

Answer 64

sugars

Question 65

Chlorophyll molecules absorb which color of light most strongly?

Choose one:
	UV
	white
	green
	red
	black

Answer 65

red