Chapter 14: Energy Generation in Mitochondria and Chloroplasts

(Q008) Which of the following statements describes the mitochondrial intermembrane space? - It is permeable to molecules with molecular mass as high as 5000 daltons. - It contains transporters for ATP molecules. - It contains proteins that are released during apoptosis. - It contains enzymes required for the oxidation of fatty acids.

It contains proteins that are released during apoptosis.

(Q007) Which of the following statements describes the mitochondrial inner membrane? - It is permeable to molecules with molecular mass as high as 5000 daltons. - It contains transporters for ATP molecules. - It contains proteins that are released during apoptosis. - It contains enzymes required for the oxidation of fatty acids.

It contains transporters for ATP molecules.

(Q024) NADH and FADH2 carry high-energy electrons that are used to power the production of ATP in the mitochondria. These cofactors are generated during glycolysis, the citric acid cycle, and the fatty acid oxidation cycle. Which molecule below can produce the most ATP? Explain your answer. - NADH from glycolysis - FADH2 from the fatty acid cycle - NADH from the citric acid cycle - FADH2 from the citric acid cycle

NADH from the citric acid cycle

(Q038) Stage 2 of photosynthesis, sometimes referred to as the dark reactions, involves the reduction of CO2 to produce organic compounds such as sucrose. What cofactor is the electron donor for carbon fixation? - H2O - NADH - FADH2 - NADPH

NADPH

(Q013) What is the final result of the electron transfers in Stage 1 of the membrane-based processes that drive ATP synthesis in mitochondria? - OH- is oxidized to O2 - pyruvate is oxidized to CO2 - O2 is reduced to H2O - H- is converted to H2

O2 is reduced to H2O

(Q003) Which of the following statements describes the phosphorylation event that occurs during the process known as "oxidative phosphorylation"? - A phosphate group is added to ADP. - ATP is hydrolyzed in order to add phosphate groups to protein substrates. - A phosphate group is added to molecular oxygen. - Inorganic phosphate is transported into the mitochondrial matrix, increasing the local phosphate concentration.

A phosphate group is added to ADP.

(Q034) Experimental evidence supporting the chemiosmotic hypothesis was gathered by using artificial vesicles containing a protein that can pump protons in one direction across the vesicle membrane to create a proton gradient. Which protein was used to generate the gradient in a highly controlled manner? - cytochrome c oxidase - NADH dehydrogenase - cytochrome c - bacteriorhodopsin

bacteriorhodopsin

(Q030) 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? - two iron atoms - one iron atom and one copper atom - one iron atom and one zinc atom - one zinc atom and one copper atom

one iron atom and one copper atom

(Q032) Which of the following is not an electron carrier that participates in the electron-transport chain? - cytochrome - quinone - rhodopsin - copper ion

rhodopsin

(Q040) The photosystems in chloroplasts contain hundreds of chlorophyll molecules, most of which are part of - plastoquinone. - the antenna complex. - the reaction center. - the ferredoxin complex.

the antenna complex.

(Q035) 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? - thylakoid space - stroma - inner membrane - thylakoid membrane

thylakoid membrane

(Q037) The ATP synthase found in chloroplasts is structurally similar to the ATP synthase in mitochondria. Given that ATP is being synthesized in the stroma, where will the F0 portion of the ATP synthase be located? - thylakoid space - stroma - inner membrane - thylakoid membrane

thylakoid membrane

(Q036) In stage 1 of photosynthesis, a proton gradient is generated and ATP is synthesized. Where do protons become concentrated in the chloroplast? - thylakoid space - stroma - inner membrane - thylakoid membrane

thylakoid space

(Q027) Which ratio of NADH to NAD+ in solution will generate the largest positive redox potential? - 1:10 - 10:1 - 1:1 - 5:1

1:10

(Q025) Which of the following statements about "redox potential" is TRUE? - Redox potential is a measure of a molecule's capacity to strip electrons from oxygen. - For molecules that have a strong tendency to pass along their electrons, the standard redox potential is negative. - The transfer of electrons from cytochrome c oxidase to oxygen has a negative redox potential. - A molecule's redox potential is a measure of the molecule's capacity to pass along electrons to oxygen.

- For molecules that have a strong tendency to pass along their electrons, the standard redox potential is negative.

(Q020) 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? - placing the mitochondria in anaerobic conditions - adding FADH2 - making the inner membrane permeable to protons - inhibiting the ATP synthase

- making the inner membrane permeable to protons

(Q014) 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. - ATP, against - protons, down - electrons, down - ADP, against

- protons, down

(Q004) 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? - 30 - 2 - 20 - 36

30

(Q043) 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? - 1:3 - 1:2 - 3:1 - 2:1

3:1

(Q002) Which of the following is NOT part of the process known as "oxidative phosphorylation"? - Molecular oxygen serves as a final electron acceptor. - FADH2 and NADH become oxidized as they transfer a pair of electrons to the electron-transport chain. - The electron carriers in the electron-transport chain toggle between reduced and oxidized states as electrons are passed along. - ATP molecules are produced in the cytosol as glucose is converted into pyruvate.

ATP molecules are produced in the cytosol as glucose is converted into pyruvate.

(Q045) 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? - electron transfers coupled to a proton pump - the reaction of oxygen with an ancestor of cytochrome c oxidase - ATP-driven proton pumps - the generation of ATP from the energy of a proton gradient FöregåendeNästa

ATP-driven proton pumps

(Q019) 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? - transmembrane H+ carrier - F1 ATPase head - peripheral stalk - central stalk

F1 ATPase head

(Q044) Which of the following statements about the possible fates of glyceraldehyde 3-phosphate is FALSE? - It can be exported from the chloroplast to the cytosol for conversion into sucrose. - It can be used to make starch, which is stored inside the stroma of the chloroplast. - It can be used as a precursor for fatty acid synthesis and stored as fat droplets in the stroma. - It can be transported into the thylakoid space for use as a secondary electron acceptor downstream of the electron-transport chain.

It can be transported into the thylakoid space for use as a secondary electron acceptor downstream of the electron-transport chain.

(Q017) During Stage 2 of oxidative phosphorylation, ATP synthesis is powered by movement of __________ ions through the __________. - H+; H+ pump - OH-; porin complex - H+; ATP synthase - elections; electron-transport chain

H+; ATP synthase

(Q012) What is the source of protons that are pumped out of the mitochondrial matrix in Stage 1 of oxidative phosphorylation? - NADH - H2O - FADH - H2S

H2O

(Q009) Which of the following statements describes the mitochondrial matrix? - It is permeable to molecules with molecular mass as high as 5000 daltons. - It contains transporters for ATP molecules. - It contains proteins that are released during apoptosis. - It contains enzymes required for the oxidation of fatty acids.

It contains enzymes required for the oxidation of fatty acids.

(Q006) Which of the following statements describes the mitochondrial outer membrane? - It is permeable to molecules with molecular mass as high as 5000 daltons. - It contains transporters for ATP molecules. - It contains proteins that are released during apoptosis. - It contains enzymes required for the oxidation of fatty acids.

It is permeable to molecules with molecular mass as high as 5000 daltons.

(Q005) Which of the following statements about mitochondrial division is TRUE? - Mitochondria divide in synchrony with the cell. - The rate of mitochondrial division is the same in all cell types. - Mitochondrial division is mechanistically similar to prokaryotic cell division. - Mitochondria cannot divide and produce energy for the cell at the same time.

Mitochondrial division is mechanistically similar to prokaryotic cell division.

(Q031) Which of the following statements is TRUE? - Ubiquinone is a small, hydrophobic protein containing a metal group that acts as an electron carrier. - A 2Fe2S iron-sulfur center carries one electron, whereas a 4Fe4S iron-sulfur center carries two electrons. - Iron-sulfur centers generally have a higher redox potential than do cytochromes. - Mitochondrial electron carriers with the highest redox potential generally contain copper ions and/or heme groups.

Mitochondrial electron carriers with the highest redox potential generally contain copper ions and/or heme groups.

(Q010) 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? - NAD+ + OH- - NAD+ + H- - NAD- + H+ - NAD + H

NAD+ + H-

(Q042) If you add a compound to illuminated chloroplasts that inhibits the NADP+ reductase, NADPH generation ceases, as expected. However, ferredoxin does not accumulate in the reduced form because it is able to donate its electrons not only to NADP+ (via NADP+ reductase) but also back to the cytochrome b6-f complex. Thus, in the presence of the compound, a "cyclic" form of photosynthesis occurs in which electrons flow in a circle from ferredoxin, to the cytochrome b6-f complex, to plastocyanin, to photosystem I, to ferredoxin. What will happen if you now also inhibit photosystem II? - Less ATP will be generated per photon absorbed. - ATP synthesis will cease. - Plastoquinone will accumulate in the oxidized form. - Plastocyanin will accumulate in the oxidized form.

Plastoquinone will accumulate in the oxidized form.

(Q028) Ubiquinone is one of two mobile electron carriers in the electron-transport chain. Where does the additional pair of electrons reside in the reduced ubiquinone molecule? - The electrons are added directly to the aromatic ring. - The electrons are added to each of two ketone oxygens on the aromatic ring. - The electrons are added to the hydrocarbon tail, which hides them inside the membrane bilayer. - Both electrons, and one proton, are added to a single ketone oxygen bound to the aromatic ring.

The electrons are added to each of two ketone oxygens on the aromatic ring.

(Q018) Which of the following statements is TRUE? - The NADH dehydrogenase complex does not pump protons across the membrane. - The pH in the mitochondrial matrix is higher than the pH in the intermembrane space. - 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. - 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.

The pH in the mitochondrial matrix is higher than the pH in the intermembrane space.

(Q033) Which of the following statements about cytochrome c is TRUE? - Cytochrome c shuttles electrons between the NADH dehydrogenase complex and cytochrome c reductase complex. - When cytochrome c becomes reduced, two cysteines (sulfur-containing amino acids) become covalently bound to a heme group. - The pair of electrons accepted by cytochrome c are added to the porphyrin ring of the bound heme group. - 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.

The pair of electrons accepted by cytochrome c are added to the porphyrin ring of the bound heme group.

(Q026) Which of the following statements is TRUE? - Only compounds with negative redox potentials can donate electrons to other compounds under standard conditions. - Compounds that donate one electron have higher redox potentials than those compounds that donate two electrons. - The ΔE0´ of a redox pair does not depend on the concentration of each member of the pair. - The free-energy change, ΔG, for an electron-transfer reaction does not depend on the concentration of each member of a redox pair.

The ΔE0´ of a redox pair does not depend on the concentration of each member of the pair.

(Q011) Electron transport is coupled to ATP synthesis in mitochondria, in chloroplasts, and in the thermophilic bacterium Methanococcus. Which of the following is likely to affect the coupling of electron transport to ATP synthesis in ALL of these systems? - a potent inhibitor of cytochrome c oxidase - the removal of oxygen - the absence of light - an ADP analog that inhibits ATP synthase

an ADP analog that inhibits ATP synthase

(Q001) The overall relationship that links bond-forming reactions to membrane transport processes in the mitochondria is called - chemiosmotic coupling. - proton pumping. - electron transfer. - ATP synthesis.

chemiosmotic coupling.

(Q015) Which of the following components of the electron-transport chain does NOT act as a proton pump? - NADH dehydrogenase - cytochrome c - cytochrome c reductase - cytochrome c oxidase

cytochrome c

(Q016) Which component of the electron-transport chain is required to combine the pair of electrons with molecular oxygen? - cytochrome c - cytochrome b-c1 complex - ubiquinone - cytochrome c oxidase

cytochrome c oxidase