Unit 4: HW 13 on Energy Generation Flashcards
Question 1: In this illustration of the structure of ATP synthase, which of the components rotate?
1, 5
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.
D. ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane.
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.
C. No, because ATP synthase is not oriented correctly.
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.
A. Brown fat cell mitochondria contain an uncoupling protein.
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
A. an electron carrier that pumps protons out of the stroma into the thylakoid space
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.
E. Ribulose 1,5-bisphosphate would be depleted, but 3-phosphoglycerate would accumulate.
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.
D. It is consumed within the chloroplast to produce glyceraldehyde 3-phosphate.
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.
C. It reduces N2 to ammonia (NH3).
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
A. cells that could pump protons
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
C. ATP
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
C. a proton (H+) gradient
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
A. pump protons across a membrane
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.
D. They evolved from bacteria engulfed by ancestral cells billions of years ago.
Which of the following organisms have mitochondria in their cells?
Choose one or more: yeasts bacteria protozoa animals plants
yeasts
protozoa
animals
plants
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
30
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.
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: Which part of the mitochondrion contains porins?
C
Question 18: Which part of the mitochondrion contains the proteins that carry out oxidative phosphorylation?
B
Question 19: Which part of the mitochondrion contains the enzymes needed to complete the oxidation of food-derived molecules?
A
Question 20: Which part of the mitochondrion contains the same mix of small molecules and inorganic ions as the cytosol?
D
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
B. inner mitochondrial membrane
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
B. pyruvate
C. fatty acids
D. amino acids
E. acetyl CoA
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
D. NADH
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.
B. Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain.
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
A. pumps protons out of the mitochondrial matrix
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)
D. oxygen (O2)
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.
C. They ferry electrons between one respiratory complex and the next.
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
E. from the matrix to the intermembrane space
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
E. from the intermembrane space to the mitochondrial matrix
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.
D. It can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.
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+
B. produce ATP
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.
E. FADH2 and NADH feed their electrons to different carriers in the electron-transport chain.
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.
A. It is more efficient than a gasoline-powered engine.
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.
C. These cells need large amounts of ATP to function normally.
Which activated carriers are produced by the citric acid cycle?
Choose one or more: FADH2 NADH CO2 NADPH GTP ATP
FADH2
NADH
GTP
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
B. import of pyruvate into the mitochondrial matrix
C. export of ATP from the mitochondrial matrix
D. import of ADP into the mitochondrial matrix
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.
D. It has a weak affinity for electrons and a negative redox potential.
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
E. donate electrons to O2
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.
B. The baby would have genetic material from three “parents” in each cell.
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
E. H2O
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.
E. Release of partially reduced oxygen radicals can damage the cell.
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.
C. It is highly favorable.
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
D. NADH produced by the citric acid cycle
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.
A. They contain a carrier protein that dissipates the proton gradient across the inner mitochondrial membrane.
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
D. oxidative phosphorylation
In the electron-transport chain in chloroplasts, which molecule serves as the final electron acceptor?
Choose one: ADP NAD+ H2O NADP+ O2
NADP+
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
E. photosystem I
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
B. photosystem I
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
C. a proton gradient across the thylakoid membrane
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
photosystem II
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
photosystem I
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.
B. Two photosystems operating in series couple their electron-energizing steps.
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
D. H2O
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.
A. It generates essentially all of the O2 in the Earth’s atmosphere.
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
photosystem II
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.
C. It is energetically unfavorable.
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
A. ATP and NADPH generated in the photosynthetic light reactions
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.
A. 1 molecule of glyceraldehyde 3-phosphate is produced, and 9 molecules of ATP + 6 molecules of NADPH are consumed.
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
E
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
Starch
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.
D. It captures light energy.
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.
B. It produces glyceraldehyde 3-phosphate in the stroma.
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.
A. The enzymes involved in stage 2 of photosynthesis are inactivated in the dark.
Photosynthesis allows plants to capture energy from sunlight to produce what?
Choose one: sugars H2O chlorophyll NADH CO2
sugars
Chlorophyll molecules absorb which color of light most strongly?
Choose one: UV white green red black
red
