CHP.14
The glyceraldehyde 3-phosphate produced by the carbon-fixation cycle can be converted into: (A) droplets of fat that are stored in the chloroplast stroma. (B) granules of starch that are stored in the chloroplast stroma. (C) the disaccharide sucrose in the plant cell cytosol. (D) All of the above (E) B and C
(D) All of the above
In mitochondria, about how many molecules of ATP can be produced from the complete oxidation of a single glucose molecule? 2 10 30 1000 to 2000 It depends on how many mitochondria are present.
30
Which of the following statements describes the mitochondrial outer membrane? (a) It is permeable to molecules with molecular mass as high as 5000 daltons. (b) It contains transporters for ATP molecules. (c) It contains proteins that are released during apoptosis. (d) It contains enzymes required for the oxidation of fatty acids.
A
Which of the following statements describes the phosphorylation event that occurs during the process known as oxidative phosphorylation? (a) A phosphate group is added to ADP. (b) ATP is hydrolyzed in order to add phosphate groups to protein substrates. (c) A phosphate group is added to molecular oxygen. (d) Inorganic phosphate is transported into the mitochondrial matrix, increasing the local phosphate concentration.
A
Which of the following drives the production of ATP from ADP and Pi by ATP synthase? A Na+ gradient A proton gradient HydrolysiS Phosphorylation Sunlight
A proton gradient
In photosynthesis, what drives the generation of ATP by ATP synthase? A proton gradient across the thylakoid membrane The absorption of light by an adjacent chlorophyll molecule The phosphorylation of ATP synthase The transfer of high-energy electrons to ATP synthase
A proton gradient across the thylakoid membrane
What is the main chemical energy currency in cells? ATP Glucose High-energy electrons NADH Water
ATP
What provides the fuel to convert CO2 into sugars in chloroplasts? A proton gradient across a membrane ATP and NADPH generated in the photosynthetic light reactions ATP generated in cellular respiration
ATP and NADPH generated in the photosynthetic light reactions
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 effect does DNP have on the transport of ATP out of the mitochondrial matrix? ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane. ATP transport will decrease because less ATP will be available to diffuse across the inner membrane. ATP transport will increase because ATP synthase will be forced to operate in the "reverse" direction. None, because ATP export is not coupled to the movement of protons across the inner membrane. None, because the inner membrane is permeable to ATP.
ATP export will decrease because its carrier exploits the difference in voltage across the inner membrane.
Which of the following organisms do not have mitochondria in their cells? Animals Bacteria Plants Protozoa Yeast
Bacteria
Which of the following statements about mitochondrial division is true? (a) Mitochondria divide in synchrony with the cell. (b) The rate of mitochondrial division is the same in all cell types. (c) Mitochondrial division is mechanistically similar to prokaryotic cell division. (d) Mitochondria cannot divide and produce energy for the cell at the same time.
C
Given that ATP is being synthesized in the stroma, where will the F0 portion of the ATP synthase be located? (a) thylakoid space (b) stroma (c) inner membrane (d) thylakoid membrane
D
What cofactor is the electron donor for carbon fixation? (a) H2O (b) NADH (c) FADH2 (d) NADPH
D
Which of the following statements is not true about the possible fates of glyceraldehyde 3-phosphate? (a) It can be exported from the chloroplast to the cytosol for conversion into sucrose. (b) It can be used to make starch, which is stored inside the stroma of the chloroplast. (c) It can be used as a precursor for fatty acid synthesis and stored as fat droplets in the stroma. (d) It can be transported into the thylakoid space for use as a secondary electron acceptor downstream of the electron-transport chain.
D
Which of the following statements is true about the electron-transport chain? Electrons are oxidized as they move from one complex to another Electrons gain energy from some complexes and lose energy to other complexes as they move along the electron-transport chain. Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain. Electrons start out at very low energy and gain energy at each transfer step.
Electrons start out at very high energy and lose energy at each transfer step along the electron-transport chain.
When a chlorophyll molecule captures light energy, what form does the energy take? Chemical-bond formation within a molecule in the reaction center of the photosystem Excited electrons Excited protons High-energy bond in ATP New electrons added to the molecule
Excited electrons
Why does a single molecule of NADH result in the production of more ATP molecules than a single molecule of FADH2 via oxidative phosphorylation? FADH2 feeds its electrons into the electron-transport chain further along the chain FADH2 is less likely then NADH to participate in the electron transport chain FADH2 does not donate its electrons in the electron transport chain NADH donates more electrons to the chain
FADH2 feeds its electrons into the electron-transport chain further along the chain
The first living cells on Earth—both prokaryotes and primitive eukaryotes—most likely generated ATP by what process? Aerobic cell respiration Fermentation Nitrogen fixation Oxidative phosphorylation Photosynthesis
Fermentation
Which of these processes does NOT involve a membrane? Generation of ATP by glycolysis Generation of ATP by oxidative phosphorylation Generation of ATP by photosynthesis in bacteria Generation of ATP by photosynthesis in plant
Generation of ATP by glycolysis
n the electron-transport chain, what provides the main reservoir for protons that are pumped across the membrane? ATP Glucose H2O NADH O2
H2O
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-sensitive proton pump purified from the prokaryote Halobacterium halobium. In each vesicle, the proton pump is oriented such that it will pump H+ into the vesicle. But the ATP synthase molecules are randomly inserted: half the vesicles will have an ATP synthase that faces inward, and half will have an ATP synthase that faces outward.When ADP and Pi are added to the external medium and the vesicles are exposed to light, what will happen? Half of the ATP synthase molecules will produce ATP, the other half will do nothing. Half of the ATP synthase molecules will produce ATP, the other half will hydrolyze ATP. Half of the ATP synthase molecules will produce ATP, the other half will pump protons into the vesicle. Half of the ATP synthase molecules will produce ATP, the other half will pump protons out of the vesicle. The vesicles will produce twice as much ATP as they would if all the ATP synthase molecules were oriented the same way.
Half of the ATP synthase molecules will produce ATP, the other half will do nothing.
What is the ratio of ATP and ADP concentrations in the cytosol of a cell? High ADP/ATP ratio High ATP/ADP ratio
High ATP/ADP ratio
In an animal cell, where are the proteins of the electron-transport chain located? In the ER membrane In the mitochondrial inner membrane In the mitochondrial matrix In the mitochondrial outer membrane In the plasma membrane
In the mitochondrial inner membrane
Which is NOT true of the carbon-fixation (Calvin) cycle? It produces energy-rich ribulose 1,5-bisphosphate. It requires ATP. It requires CO2. It requires high-energy electrons from NADPH It requires oxygen.
It requires oxygen.
In mitochondria, what is the final electron acceptor in the electron-transport chain? ADP Carbon dioxide (CO2) Molecular oxygen (O2) NADH and FADH2 Water (H2O)
Molecular oxygen (O2)
The electron-transport chain in mitochondria accepts high-energy electrons directly from: acetyl CoA. ATP. NADH and FADH2. pyruvate. water.
NADH and FADH2.
Iron-sulfur clusters tend to have a relatively low affinity for electrons. Which component of the electron-transport chain most likely contains an iron-sulfur cluster? Cytochrome c Cytochrome c oxidase complex Cytochrome c reductase complex NADH dehydrogenase complex Ubiquinone
NADH dehydrogenase complex
Which of the following is true? NADH has a strong affinity for electrons and a negative redox potential. NADH has a strong affinity for electrons and a positive redox potential. NADH has a weak affinity for electrons and a negative redox potential. NADH has a weak affinity for electrons and a positive redox potential.
NADH has a weak affinity for electrons and a negative redox potential.
In the electron-transport chain in chloroplasts, which molecule serves as the final electron acceptor? ADP H2O NAD+ NADP+ O2
NADP+
Earth's history, with the rise of cyanobacteria, what molecule began accumulating in the atmosphere for the first time? CO2 H2O N2 O2
O2
Which photosystem is able to boost electrons to the very high energy level needed to make NADPH from NADP+? Photosystem I Photosystem II
Photosystem I
Some types of bacteria can survive under both aerobic and anaerobic conditions. Regardless of whether oxygen is present, these cells maintain a proton gradient across the plasma membrane to drive ATP synthesis and the import of nutrients. Under aerobic conditions, a H+ gradient across the plasma membrane is produced by the transfer of electrons along the respiratory chain. When oxygen is present, what do you think takes place in the plasma membrane of these bacteria? ATP synthase hydrolyzes ATP, pumping protons into the cell to help maintain the H+ gradient. ATP synthase hydrolyzes ATP, pumping protons out of the cell to help maintain the H+ gradient. Nutrients are imported by carriers that take advantage of the proton gradient produced by electron transport along the mitochondrial membrane. Protons flow into the bacterium through ATP synthase, generating ATP. Protons flow out of the cell through ATP synthase, generating ATP.
Protons flow into the bacterium through ATP synthase, generating ATP.
Carbon fixation occurs in the second stage of photosynthesis, during the so-called "dark 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? Both would accumulate. Both would be depleted. Nothing would happen because the Calvin cycle is not dependent on light. Ribulose 1,5-bisphosphate would accumulate, but 3-phosphoglycerate would be depleted. Ribulose 1,5-bisphosphate would be depleted, but 3-phosphoglycerate would accumulate.
Ribulose 1,5-bisphosphate would be depleted, but 3-phosphoglycerate would accumulate.
What occurs when ATP synthase operates "in reverse" and pumps H+ across a membrane against its electrochemical proton gradient? The ATP synthase catalyzes the formation of ATP from ADP and Pi. The ATP synthase hydrolyzes ATP to form ADP and Pi. The ATP synthase transports ATP across the membrane. The ATP synthase transports Na+ in the opposite direction across the membrane. The ATP synthase transports nutrients in the opposite direction across the membrane.
The ATP synthase hydrolyzes ATP to form ADP and Pi.
Which of the following is NOT true of mitochondria? Inside a cell, they are mobile, constantly changing shape and position. They are replaced by chloroplasts in plants. They are similar in size and shape to bacteria. They contain an outer membrane, an inner membrane, and two internal compartments. They contain their own DNA and RNA.
They are replaced by chloroplasts in plants.
Which of the following statements is false? the iron-sulfur centers in NADH dehydrogenase relatively poor electron acceptors Ubiquinones associated with the inner mitochondrial membrane as a protein-bound electron carrier molecule cytochrome C oxidase binds 02using an iron-heme group where four electrons are shuttled one at a time Ubiquinone can transfer one or two electrons
Ubiquinones associated with the inner mitochondrial membrane as a protein bound electron carrier molecule
Which has the highest redox potential? Ferredoxin NADPH Plastocyanin Plastoquinone Water
Water
Which of the following statements is NOT true of electron transfer in the electron-transport chain? Each electron transfer is an oxidation-reduction reaction. Electrons move toward molecules with a high redox potential. NADH has a relatively low electron affinity. NADH is a strong electron donor. When an electron carrier accepts an electron, it becomes oxidized.
When an electron carrier accepts an electron, it becomes oxidized.
When an electron is removed from the reaction center of photosystem II, how is the missing electron then replenished? With an electron from a hydrogen ion With an electron from sunlight With an electron removed from photosystem I With an electron removed from water
With an electron removed from water
In stage 1 of photosynthesis, a proton gradient is generated and ATP is synthesized. Where do protons become concentrated in the chloroplast? (a) thylakoid space (b) stroma (c) inner membrane (d) thylakoid membrane
a
Modern eukaryotes depend on mitochondria to generate most of the cell's ATP. How many molecules of ATP can a single molecule of glucose generate? (a) 30 (b) 2 (c) 20 (d) 36
a
The link between bond-forming reactions and membrane transport processes in the mitochondria is called __________________. (a) chemiosmotic coupling. (b) proton pumping. (c) electron transfer. (d) ATP synthesis.
a
Which of the following statements best describes how the diffusion of ubiquinone is controlled in order to ensure its proximity to the other enzyme complexes? (a) Ubiquinone is anchored directly in the inner mitochondrial membrane via its hydrocarbon tail, and can only diffuse laterally. (b) Ubiquinone is present at high concentrations, minimizing the impact of diffusion on the electron-transport chain. (c) Ubiquinone becomes covalently attached to the other enzyme complexes. (d) The intermembrane space in the mitochondrion is relatively small, and therefore the random diffusion of these molecules is not a problem.
a
Which ratio of NADH to NAD+ in solution will generate the largest positive redox potential? (a) 1:10 (b) 10:1 (c) 1:1 (d) 5:1
a
Why might rubisco have evolved with an inability to distinguish between Co2 and O2? A) Rubisco may have evolved at a time when atmospheric O2 levels were virtually nonexistent B) Rubisco possesses four subunits C) Rubisco may have evolved at a time when atmospheric CO2 levels were virtually nonexistent D) Rubisco evolved when atmospheric O2 levels were high
a
As electrons move through the electron-transport chain, they are passed from: a carrier molecule of higher electron affinity to a carrier molecule of lower electron affinity. a carrier molecule of lower electron affinity to a carrier molecule of higher electron affinity.
a carrier molecule of lower electron affinity to a carrier molecule of higher electron affinity.
During photosynthesis, charge separation takes place when: an excited chlorophyll special pair passes an electron to a set of electron carriers in the antenna complex, leaving behind a negative charge. an excited chlorophyll special pair passes an electron to a set of electron carriers in the antenna complex, leaving behind a positive charge. an excited chlorophyll special pair passes an electron to a set of electron carriers in the reaction center, leaving behind a negative charge. an excited chlorophyll special pair passes an electron to a set of electron carriers in the reaction center, leaving behind a positive charge. energy jumps randomly from one chlorophyll molecule to another in the antenna complex. light energy is captured by a chlorophyll molecule in the antenna complex.
an excited chlorophyll special pair passes an electron to a set of electron carriers in the reaction center, leaving behind a positive charge.
Cytochrome c oxidase is an enzyme complex that uses metal ions to help coordinate the transfer of four electrons to O2. Which metal atoms are found in the active site of this complex? (a) two iron atoms (b) one iron atom and one copper atom (c) one iron atom and one zinc atom (d) one zinc atom and one copper atom
b
In the electron-transport chain in chloroplasts, ________-energy electrons are taken from __________. (a) high; H2O. (b) low; H2O. (c) high; NADPH. (d) low; NADPH.
b
NADH contains a high-energy bond that, when cleaved, donates a pair of electrons to the electron-transport chain. What are the immediate products of this bond cleavage? (a) NAD+ + OH- (b) NAD+ + H- (c) NAD- + H+ (d) NAD + H
b
Osmosis describes the movement of water across a biological membrane and down its concentration gradient. In chemiosmosis, useful energy is harnessed by the cell from the movement of _______________ across the inner mitochondrial membrane into the matrix _________________ a concentration gradient. (a) ATP, against (b) protons, down (c) electrons, down (d) ADP, against
b
The mitochondrial ATP synthase consists of several different protein subunits. Which subunit binds to ADP + Pi and catalyzes the synthesis of ATP as a result of a conformational change? (a) transmembrane H+ carrier (b) F1 ATPase head (c) peripheral stalk (d) central stalk
b
The photosystems in chloroplasts contain hundreds of chlorophyll molecules, most of which are part of _______________. (a) plastoquinone. (b) the antenna complex. (c) the reaction center. (d) the ferredoxin complex.
b
The water-splitting step in photosynthesis: (A) consumes protons and thereby depletes the proton gradient across the thylakoid membrane. (B) generates essentially all of the O2 in the Earth's atmosphere. (C) is catalyzed by an enzyme containing an iron-sulfur cluster. (D) occurs on the stromal side of the thylakoid membrane. (E) takes place during the dark reactions. (F) All of the above
b
Where does the additional pair of electrons reside in the reduced ubiquinone molecule? (a) The electrons are added directly to the aromatic ring. (b) The electrons are added to each of the two ketone oxygens on the aromatic ring. (c) The electrons are added to the hydrocarbon tail, which hides them inside the membrane bilayer. (d) Both electrons, and one proton, are added to single ketone oxygen bound to the aromatic ring.
b
Which of the following components of the electron-transport chain does not act as a proton pump? (a) NADH dehydrogenase (b) cytochrome c (c) cytochrome c reductase (d) cytochrome c oxidase
b
Which of the following statements about "redox potential" is true? (a) Redox potential is a measure of a molecule's capacity to strip electrons from oxygen. (b) For molecules that have a strong tendency to pass along their electrons, the standard redox potential is negative. (c) The transfer of electrons from cytochrome c oxidase to oxygen has a negative redox potential. (d) A molecule's redox potential is a measure of the molecule's capacity to pass along electrons to oxygen.
b
Which of the following statements describes the mitochondrial inner membrane? (a) It is permeable to molecules with molecular mass as high as 5000 daltons. (b) It contains transporters for ATP molecules. (c) It contains proteins that are released during apoptosis. (d) It contains enzymes required for the oxidation of fatty acids.
b
Which of the following statements is true? (a) The NADH dehydrogenase complex can pump more protons than can the cytochrome b-c1 complex. (b) The pH in the mitochondrial matrix is higher than the pH in the intermembrane space. (c) The proton concentration gradient and the membrane potential across the inner mitochondrial membrane tend to work against each other in driving protons from the intermembrane space into the matrix. (d) The difference in proton concentration across the inner mitochondrial membrane has a much larger effect than the membrane potential on the total proton-motive force.
b
Which of the following types of ion movement might be expected to require co-transport of protons from the mitochondrial intermembrane space to the matrix, inasmuch as it could not be driven by the membrane potential across the inner membrane? (Assume that each ion being moved is moving against its concentration gradient.) (a) import of Ca2+ into the matrix from the intermembrane space (b) import of acetate ions into the matrix from the intermembrane space (c) exchange of Fe2+ in the matrix for Fe3+ in the intermembrane space (d) exchange of ATP from the matrix for ADP in the intermembrane space
b
Bongkrekic acid is an antibiotic that inhibits the ATP/ADP transport protein in the inner mitochondrial membrane. Which of the following will allow electron transport to occur in mitochondria treated with bongkrekic acid? (a) placing the mitochondria in anaerobic conditions (b) adding FADH2 (c) making the inner membrane permeable to protons (d) inhibiting the ATP synthase
c
How do C4 and CAM plants overcome the negative effects of photorespiration? A) They chemically alter O2 before it gets to the enzyme B)They destroy O2 C)They employ mechanisms that increase the CO2/O2 ration to which Rubisco molecules are exposed D) They destroy CO2
c
In oxidative phosphorylation, ATP production is coupled to the events in the electron-transport chain. What is accomplished in the final electron-transfer event in the electron-transport chain? (a) OH- is oxidized to O2 (b) pyruvate is oxidized to CO2 (c) O2 is reduced to H2O (d) NAD+ is reduced to NADH
c
Oxidative phosphorylation, as it occurs in modern eukaryotes, is a complex process that probably arose in simple stages in primitive bacteria. Which mechanism is proposed to have arisen first as this complex system evolved? (a) electron transfers coupled to a proton pump (b) the reaction of oxygen with an ancestor of cytochrome c oxidase (c) ATP-driven proton pumps (d) the generation of ATP from the energy of a proton gradient
c
Stage 1 of oxidative phosphorylation requires the movement of electrons along the electron-transport chain coupled to the pumping of protons into the intermembrane space. What is the final result of these electron transfers? (a) OH- is oxidized to O2 (b) pyruvate is oxidized to CO2 (c) O2 is reduced to H2O (d) H- is converted to H2
c
The enzyme ribulose bisphosphate carboxylase (Rubisco) normally adds carbon dioxide to ribulose 1,5-bisphosphate. However, it will also catalyze a competing reaction in which O2 is added to ribulose 1,5-bisphosphate to form 3-phosphoglycerate and phosphoglycolate. Assume that phosphoglycolate is a compound that cannot be used in any further reactions. If O2 and CO2 have the same affinity for Rubisco, which of the following is the lowest ratio of CO2 to O2 at which a net synthesis of sugar can occur? (a) 1:3 (b) 1:2 (c) 3:1 (d) 2:1
c
Which of the following is not an electron carrier that participates in the electron-transport chain? (a) cytochrome (b) quinone (c) rhodopsin (d) copper ion
c
Which of the following statements about cytochrome c is true? (a) Cytochrome c shuttles electrons between the NADH dehydrogenase complex and cytochrome c reductase complex. (b) When cytochrome c becomes reduced, two cysteines (sulfur-containing amino acids) become covalently bound to a heme group. (c) The pair of electrons accepted by cytochrome c are added to the porphyrin ring of the bound heme group. (d) Cytochrome c is the last protein in the electron-transport chain, passing its electrons directly to molecular oxygen, a process that reduces O2 to H2O.
c
Which of the following statements describes the mitochondrial intermembrane space? (a) It is permeable to molecules with molecular mass as high as 5000 daltons. (b) It contains transporters for ATP molecules. (c) It contains proteins that are released during apoptosis. (d) It contains enzymes required for the oxidation of fatty acids.
c
Which of the following statements is true? (a) Only compounds with negative redox potentials can donate electrons to other compounds under standard conditions. (b) Compounds that donate one electron have higher redox potentials than those compounds that donate two electrons. (c) The ΔE0′ of a redox pair does not depend on the concentration of each member of the pair. (d) The free-energy change, ΔG, for an electron-transfer reaction does not depend on the concentration of each member of a redox pair.
c
ATP synthase: can break down ATP but cannot produce it. can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient. can produce ATP but cannot break it down.
can either produce or break down ATP depending on the magnitude of the electrochemical proton gradient.
Which of the following statements is true? The electron-transport proteins utilized in stage 1 of glycosynthesis resides in the inner membrane of the chloroplast stage2 of photosynthesis involves a cycle of reactions that directly depend on energy derived from sunlight none of these are true carbon fixation can be described as a process by which gaseous carbon-containing molecules are captured and incorporated into biological hydrocarbon molecules
carbon fixation can be described as a process by which gaseous carbon containing molecules are captured and incorporated into biological hydrocarbon molecules
Photosynthesis is a process that takes place in chloroplasts and uses light energy to generate high-energy electrons, which are passed along an electron-transport chain. Where are the proteins of the electron-transport chain located in chloroplasts? (a) thylakoid space (b) stroma (c) inner membrane (d) thylakoid membrane
d
Which component of the electron-transport chain is required to combine the pair of electrons with molecular oxygen? (a) cytochrome c (b) cytochrome b-c1 complex (c) ubiquinone (d) cytochrome c oxidase
d
Which of the following is likely to affect the coupling of electron transport to ATP synthesis in all of these systems? (a) a potent inhibitor of cytochrome c oxidase (b) the removal of oxygen (c) the absence of light (d) an ADP analog that inhibits ATP synthase
d
Which of the following is not part of the process known as oxidative phosphorylation? (a) Molecular oxygen serves as a final electron acceptor. (b) FADH2 and NADH become oxidized as they transfer a pair of electrons to the electron-transport chain. (c) The electron carriers in the electron-transport chain toggle between reduced and oxidized states as electrons are passed along. (d) ATP molecules are produced in the cytosol as glucose is converted into pyruvate.
d
Which of the following statements describes the mitochondrial matrix? (a) It is permeable to molecules with molecular mass as high as 5000 daltons. (b) It contains transporters for ATP molecules. (c) It contains proteins that are released during apoptosis. (d) It contains enzymes required for the oxidation of fatty acids.
d
Which of the following statements is true? (a) Ubiquinone is a small, hydrophobic protein containing a metal group that acts as an electron carrier. (b) A 2Fe2S iron-sulfur center carries one electron, whereas a 4Fe4S center carries two. (c) Iron-sulfur centers generally have a higher redox potential than do cytochromes. (d) Mitochondrial electron carriers with the highest redox potential generally contain copper ions and/or heme groups.
d
Which protein was used to generate the gradient in a highly controlled manner? (a) cytochrome c oxidase (b) NADH dehydrogenase (c) cytochrome c (d) bacteriorhodopsin
d
NADH has a strong tendency to: accept electrons. donate electrons. either donate or accept electrons depending on the electrochemical proton gradient.
donate electrons.
The organelles that produce ATP in eukaryotic animal cells: evolved from bacteria engulfed by ancestral cells billions of years ago. harbor eukaryotic-like biosynthetic machinery for making RNA. have a separate set of DNA that contains many of the same genes found in the nucleus. reproduce sexually.
evolved from bacteria engulfed by ancestral cells billions of years ago.
During stage 1 of photosynthesis, excited electrons move: from an electron carrier to NADP+ to ATP synthase. from NADP+ to a mobile electron carrier to the chlorophyll special pair. from sunlight to the chlorophyll special pair. from the chlorophyll special pair to an electron carrier to NADP+. from the stroma to the thylakoid membrane to the thylakoid space.
from the chlorophyll special pair to an electron carrier to NADP+.
It is energetically favorable for protons to flow: from the intermembrane space to the mitochondrial matrix. from the mitochondrial matrix to the intermembrane space.
from the intermembrane space to the mitochondrial matrix.
The electron-transport chain pumps protons: from the cytosol to the intermembrane space. from the intermembrane space to the cytosol. from the intermembrane space to the matrix from the matrix to the cytosol. from the matrix to the intermembrane space.
from the matrix to the intermembrane space.
Which of the following is not a direct source of fuel for mitochondria? Acetyl CoA Amino acids Fatty acids Glucose Pyruvate
glucose
When the difference in redox potential between two molecules is highly positive, the transfer of electrons between them is: highly favorable. highly improbable. highly inefficient. highly unfavorable. prohibited by the laws of thermodynamics.
highly favorable.
In eukaryotic cells, the conversion of CO2 and H2O to sugar takes place: along the plasma membrane. in the chloroplast stroma. in the cytosol. in the mitochondrial matrix. in the thylakoid.
in the chloroplast stroma.
The energy efficiency of cell respiration: is about the same as that of a gasoline-powered engine. cannot be compared to that of a gasoline-powered engine. is less than that of a gasoline-powered engine. is more than that of a gasoline-powered engine.
is more than that of a gasoline-powered engine.
What electron acceptor allows an organism to completely break down organic molecules into CO2 and H2O and thereby release a large amount of energy that can be harnessed by the cell to do work? CO2 H2O NADH O2 Pyruvate
o2
Stage 1 of photosynthesis is in large part equivalent to: mitosis. glycolysis. oxidative phosphorylation. the citric acid cycle.
oxidative phosphorylation.
When O2 accepts electrons in the electron-transport chain, O2 becomes: oxidized. reduced.
oxidized.
When protons move down their electrochemical gradient into the mitochondrial matrix, they: consume ATP. produce ATP. produce NADH. produce NAD+. move electrons through the respiratory chain.
produce ATP.
In the electron-transport chain, as electrons move along a series of carriers, they release energy that is used to: hydrolyze ATP. oxidize food molecules. phosphorylate ADP to form ATP. pump protons across a membrane. split water into protons and oxygen.
pump protons across a membrane.
The movement of electrons through the electron-transport chain in mitochondria: consumes ATP. produces NADH. produces oxygen. pumps ATP across the inner mitochondrial membrane. pumps protons out of the matrix.
pumps protons out of the matrix.
Chlorophyll molecules absorb which color of light most strongly? Black Green Red UV White
red
Nitrogen fixation: can be used to generate a H+ gradient. converts CO2 and H2O into sugars. promoted the evolution of ancient cells by allowing them to convert N2 to NO2 near thermal vents reduces N2 to ammonia (NH3). requires a small energy input and is thus energetically favorable.
reduces N2 to ammonia (NH3).
During very active periods of photosynthesis, the glyceraldehyde 3-phosphate generated by carbon fixation in the chloroplast stroma is stored as: ATP. glycogen. pyruvate. starch.
starch.
Photosynthesis allows plants to capture energy from sunlight to produce: chlorophyll. CO2. H2O. NADH. sugars.
sugars.
Ubiquinone has a redox potential of +30 mV, while cytochrome c has a redox potential of +230 mV. In the electron-transport chain, electrons flow from: cytochrome c to ubiquinone. ubiquinone to cytochrome c.
ubiquinone to cytochrome c.