Cellular Respiration

A molecule that is phosphorylated Select one: a. has less energy than before its phosphorylation and therefore less energy for cellular work. b. has a decreased chemical reactivity, it is less likely to provide energy for cellular work. c. has an increased chemical reactivity, it is primed to do cellular work. d. is unchanged in its capacity to do cellular work. Feedback

C

During aerobic respiration, electrons travel downhill in which sequence? Select one: a. glucose to ATP to electron transport chain to NADH b. food to citric acid cycle to ATP to NAD+ c. food to NADH to electron transport chain to oxygen d. food to glycolysis to citric acid cycle to NADH to ATP

C

During the chemiosmosis phase of oxidative phosphorylation, potential energy stored during the electron transport phase is converted to energy stored in the form of: Select one: a. NADH b. a proton gradient c. ATP d. lipid

C

During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from? Select one: a. carbon dioxide (CO2) b. pyruvate (C3H3O3-) c. glucose (C6H12O6) d. molecular oxygen (O2)

D

In aerobic metabolism, most of the ATP produced by the oxidation of glucose to carbon dioxide is produced by Select one: a. oxidative phosphorylation. b. glycolysis. c. the Krebs cycle. d. the Calvin cycle.

A

In cellular respiration, the energy for most ATP synthesis is supplied by Select one: a. a proton gradient across a membrane. b. transferring electrons from organic molecules to pyruvate. c. high energy phosphate bonds in organic molecules. d. converting oxygen to ATP.

A

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? Select one: a. It increases the surface for oxidative phosphorylation. b. It allows for an increased rate of the citric acid cycle. c. It increases the surface for substrate-level phosphorylation. d. It allows for an increased rate of glycolysis.

A

In prokaryotes, the respiratory electron transport chain is located Select one: a. in the plasma membrane. b. in the cytoplasm. c. in the mitochondrial inner membrane. d. in the mitochondrial outer membrane.

A

In the reaction shown below CH4 + 2 O2 → CO2 + energy + 2 H2O Select one: a. CH4 is oxidized and O2 is reduced b. CH4 is reduced and O2 is oxidized c. CH4 and O2 are oxidized d. CH4 and O2 are reduced

A

Most of the energy released during cellular respiration ends up: Select one: a. being lost as heat b. being used to make NADH c. being used to make lipids d. being used to make ATP

A

The ATP made during fermentation is generated by which of the following? Select one: a. substrate-level phosphorylation b. aerobic respiration c. chemiosmosis d. oxidative phosphorylation

A

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is Select one: a. oxygen. b. water. c. ADP. d. NAD+.

A

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction Select one: a. loses electrons and loses energy b. loses electrons and gains energy c. gains electrons and gains energy d. gains electrons and loses energy

A

The purpose of fermentation reactions is Select one: a. to regenerate NAD+ so glycolysis can continue b. to slow down cellular oxygen consumption when oxygen is scarce c. to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions d. to make additional ATP when respiration can't make ATP fast enough

A

To sustain high rates of glycolysis under anaerobic conditions, cells require Select one: a. regeneration of NAD+ b. regeneration of NADH c. all of these answers are correct d. oxidative phosphorylation of ATP.

A

What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ Select one: a. pyruvate b. lactate c. NAD+ d. NADH

A

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the direct result is the Select one: a. creation of a proton-motive force. b. lowering of pH in the mitochondrial matrix. c. formation of ATP. d. reduction of NAD+.

A

Which of the following is an important difference between aerobic and anaerobic respiration Select one: a. All of these answers are correct. Incorrect b. Anaerobic respiration results in the production of lactic acid (lactate) or ethanol. c. Aerobic, but not anaerobic, respiration makes use of the citric acid cycle. d. The electron transport chain used in aerobic respiration uses O2 as the final electron acceptor whereas the electron transport chain used in anaerobic respiration uses something other than O2 as the final electron acceptor.

A

Which of the following shows the molecules in the order of least to most electronegative? Select one: a. NADH, e- transport chain, O2 b. O2, e- transport chain, NADH c. NADH, O2, e- transport chain d. O2, NADH, e- transport chain

A

Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy Select one: a. C6H12O6 is oxidized and O2 is reduced. b. O2 is oxidized and H2O is reduced. c. C6H12O6 is reduced and CO2 is oxidized. d. CO2 is reduced and O2 is oxidized.

A

Why is less ATP produced by anaerobic respiration than by aerobic respiration? Select one: a. Anaerobic respiration uses a final electron acceptor that is less electronegative than O2, which is used as the final electron acceptor in aerobic respiration. b. Anaerobic respiration does not make use of an electron transport chain. c. All of these answers are correct. d. Anaerobic respiration does not make use of the citric acid cycle.

A

A mutation in yeast makes it unable to convert pyruvate to ethanol. How will this mutation affect these yeast cells? Select one: a. The mutant yeast will grow anaerobically only when given glucose. b. The mutant yeast will be unable to grow anaerobically. c. The mutant yeast will die because they cannot regenerate NAD+ from NAD. d. The mutant yeast will be unable to metabolize glucose.

B

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? Select one: a. fermentation and glycolysis b. oxidation of pyruvate to acetyl CoA and the citric acid cycle c. the citric acid cycle and oxidative phosphorylation d. glycolysis and the oxidation of pyruvate to acetyl CoA

B

Drugs known as uncouplers facilitate diffusion of protons across the membrane. When such a drug is added, what will happen to ATP synthesis and oxygen consumption, if the rates of glycolysis and the citric acid cycle stay the same? Select one: a. Both ATP synthesis and oxygen consumption will increase b. ATP synthesis will decrease; oxygen consumption will stay the same c. ATP synthesis will increase; oxygen consumption will decrease d. Both ATP synthesis and oxygen consumption will decrease

B

During the chemiosmosis phase of oxidative phosphorylation, potential energy stored during the electron transport phase is converted to energy stored in the form of: Select one: a. a proton gradient b. ATP c. NADH d. lipid Feedback

B

In a mitochondrion, if the matrix ATP concentration is high, and the intermembrane space proton concentration is too low to generate sufficient proton-motive force, then Select one: a. ATP synthase will hydrolyze ATP and pump protons into the matrix. b. ATP synthase will hydrolyze ATP and pump protons into the intermembrane space. c. ATP synthase will stop working. d. ATP synthase will increase the rate of ATP synthesis.

B

In addition to ATP, what are the end products of glycolysis? Select one: a. CO2 and pyruvate b. NADH and pyruvate c. CO2 and NADH d. CO2 and H2O

B

In aerobic metabolism, most of the ATP produced by the oxidation of glucose to carbon dioxide is produced by Select one: a. the Krebs cycle. b. oxidative phosphorylation. c. the Calvin cycle. d. glycolysis.

B

In mitochondria, exergonic redox reactions Select one: a. are the source of energy driving prokaryotic ATP synthesis. b. provide the energy that establishes the proton gradient. c. are directly coupled to substrate-level phosphorylation. d. reduce carbon atoms to carbon dioxide.

B

In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of Select one: a. ATP, NADH, and pyruvate. b. ATP, CO2, and ethanol (ethyl alcohol). c. ATP, CO2, and lactate. d. ATP, pyruvate, and oxygen.

B

What is the term for metabolic pathways that release stored energy by breaking down complex molecules? Select one: a. anabolic pathways b. catabolic pathways c. thermodynamic pathways d. bioenergetic pathways

B

When comparing electronegativities, Select one: a. oxygen is more electronegative than NADH b. all of these answers are correct c. oxygen is more electronegative than all of the components of the electron transport chain d. oxygen is more electronegative than FADH2

B

When electrons move closer to a more electronegative atom, what happens? Select one: a. Energy is consumed and he more electronegative atom is oxidized Incorrect b. Energy is released and the more electronegative atom is reduced c. Energy is released and he more electronegative atom is oxidized d. Energy is consumed and the more electronegative atom is reduced

B

Where is ATP synthase located in the mitochondrion? Select one: a. cytosol b. inner membrane c. outer membrane d. mitochondrial matrix

B

Which of the following occur in both aerobic and anaerobic respiration? Select one: a. glycolysis b. all of these answers are correct c. citric acid cycle d. an electron transport chain

B

Which of the following statements describes NAD+? Select one: a. NAD+ has more chemical energy than NADH. b. NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. c. NAD+ can donate electrons for use in oxidative phosphorylation. d. In the absence of NAD+, glycolysis can still function.

B

Why is glycolysis described as having an investment phase and a payoff phase? Select one: a. It both splits molecules and assembles molecules. b. It first uses two stored ATP and then forms four ATP, for a net increase of two ATP. c. It uses glucose and generates pyruvate. d. It attaches and detaches phosphate groups.

B

One function of both alcohol fermentation and lactic acid fermentation is to Select one: a. reduce FAD+ to FADH2. b. oxidize NADH to NAD+. c. reduce FADH2 to FAD+. d. reduce NAD+ to NADH.

B Fermentation is necessary to "re-cycle" the NADH formed during glycolysis to NAD+ so that the reactions of glycolysis can continue. In other words, during glycolysis, NAD+ is converted to NADH. In order for glycolysis to continue, cells need a continuous supply of NAD+. During aerobic respiration, that supply of NAD+ is provided by oxidation of NADH via the electron transport chain. If that isn't possible (e.g. due to oxygen levels being too low), some cells will produce NAD+ from NADH via the reactions of fermentation.

Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells? Select one: a. cytosol b. mitochondrial matrix c. mitochondrial intermembrane space d. mitochondrial outer membrane

C

Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." These little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. These inside-out membrane vesicles Select one: a. will make ATP from ADP and Pi if transferred to a pH 4 buffered solution after incubation in a pH 7 buffered solution. b. will hydrolyze ATP to pump protons out of the interior of the vesicle to the exterior. c. will become acidic inside the vesicles when NADH is added. d. will become alkaline inside the vesicles when NADH is added.

C

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of Select one: a. competitive inhibition. b. an enzyme requiring a cofactor. c. allosteric regulation. d. the specificity of enzymes for their substrates.

C

In the reaction shown below Na and Cl → Na+ and Cl- Select one: a. Na is reduced and Cl is oxidized b. Na and Cl are reduced c. Na is oxidized and Cl is reduced d. Na and Cl are oxidized

C

Inside an active mitochondrion, most electrons follow which pathway? Select one: a. glycolysis → NADH → oxidative phosphorylation → ATP → oxygen b. electron transport chain → citric acid cycle → ATP → oxygen c. citric acid cycle → NADH → electron transport chain → oxygen d. pyruvate → citric acid cycle → ATP → NADH → oxygen Feedback

C

Pyruvate is transported into mitochondria by Select one: a. an antiporter that transports pyruvate down its concentration gradient while transporting protons up their electrochemical gradient. b. a symporter that transports pyruvate down its concentration gradient while transporting protons up their electrochemical gradient. c. a symporter that transports pyruvate up its concentration gradient while transporting protons down their electrochemical gradient. d. an antiporter that transports pyruvate up its concentration gradient while transporting protons down their electrochemical gradient.

C

Redox reactions Select one: a. can result in a transfer of electrons b. can result in a change in electron sharing in covalent bonds c. both "a" and "b" are correct d. none of these answers is correct

C

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is Select one: a. the thermodynamically favorable transfer of phosphate from glycolysis and the citric acid cycle intermediates to molecules of ADP. b. the final transfer of electrons to oxygen. c. the proton-motive force across the inner mitochondrial membrane. d. the thermodynamically favorable flow of electrons from NADH to the mitochondrial electron transport carriers.

C

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of Select one: a. active transport. b. allosteric regulation. c. an endergonic reaction coupled to an exergonic reaction. d. a reaction with a positive ΔG .

C

What is proton-motive force? Select one: a. the force that moves hydrogen into the intermembrane space b. the force required to remove an electron from hydrogen c. the force that moves hydrogen to NAD+ d. the force exerted on a proton by a transmembrane proton concentration gradient

C

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes Select one: a. hydrolyzed. b. reduced. c. oxidized. d. hydrogenated. Feedback

C

When comparing electronegativities, Select one: a. oxygen is more electronegative than FADH2 b. oxygen is more electronegative than all of the components of the electron transport chain c. all of these answers are correct d. oxygen is more electronegative than NADH

C

When skeletal muscle cells continue to do work under conditions of insufficient oxygen (e.g. anaerobic exercise), they become fatigued and painful. This is now known to be caused by Select one: a. increase in sodium ions. b. buildup of pyruvate. c. buildup of lactate. d. increase in ethanol.

C

Where does glycolysis take place in eukaryotic cells? Select one: a. mitochondrial inner membrane b. mitochondrial intermembrane space c. cytosol d. mitochondrial matrix

C

Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate? Select one: a. citrate b. lactate c. acetyl CoA d. glyceraldehydes-3-phosphate

C

Which of the following most accurately describes what happens along the electron transport chain? Select one: a. ATP is generated at each step. b. Energy of the electrons increases at each step. c. Each electron carrier alternates between being reduced and being oxidized. d. Molecules in the chain give up some of their potential energy.

C

You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave her body? Select one: a. It was converted to heat and then released. b. It was converted to ATP, which weighs much less than fat. c. It was released as CO2 and H2O. d. It was converted to urine and eliminated from the body.

C

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water? Select one: a. oxidation of pyruvate to acetyl CoA b. citric acid cycle c. oxidative phosphorylation (chemiosmosis) d. glycolysis

C Glycolysis and the citric acid cycle both produce a small amount of ATP via substrate-level phosphorylation. Far more ATP is produced during oxidative phosphorylation, when electrons are transported from NADH to oxygen, resulting in the creation of a proton gradient that then provides the energy needed for ATP synthesis by ATP synthase.

A molecule that is phosphorylated Select one: a. has been reduced as a result of a redox reaction involving the loss of an inorganic phosphate. b. has less energy than before its phosphorylation and therefore less energy for cellular work. c. has a decreased chemical reactivity; it is less likely to provide energy for cellular work. d. has an increased chemical potential energy; it is primed to do cellular work.

D

An electron loses potential energy when it Select one: a. shifts to a less electronegative atom. b. increases its kinetic energy. c. moves further away from the nucleus of the atom. d. shifts to a more electronegative atom.

D

During cellular respiration, acetyl CoA accumulates in which location? Select one: a. mitochondrial intermembrane space b. mitochondrial inner membrane c. cytosol d. mitochondrial matrix

D

During cellular respiration, what is the direction of energy flow? Select one: a. Chemical bonds in food - to a proton gradient - to NADH - to chemical bonds in ATP b. Chemical bonds in food - to NADH - to chemical bonds in ATP - to a proton gradient c. Chemical bonds in food - to a proton gradient - to chemical bonds in ATP - to NADH d. Chemical bonds in food - to NADH - to a proton gradient - to chemical bonds in ATP

D

Even though plants carry on photosynthesis, plant cells still use their mitochondria for oxidation of pyruvate. When and where will this occur? Select one: a. in nonphotosynthesizing cells only b. in cells that are storing glucose only c. only in photosynthetic cells in the light, while photosynthesis occurs concurrently d. in all cells all the time

D

In chemiosmotic phosphorylation, what is the most direct source of energy that is used to convert ADP + inorganic phosphate to ATP? Select one: a. No external source of energy is required because the reaction is exergonic. b. energy released from movement of protons through ATP synthase, against the electrochemical gradient c. energy released as electrons flow through the electron transport system d. energy released from movement of protons through ATP synthase, down the electrochemical gradient

D

In the reaction shown below C6H12O6 + 6 O2 → 6 CO2 + energy + 6 H2O Select one: a. C6H12O6 is reduced and O2 is oxidized b. C6H12O6 and O2 are oxidized c. C6H12O6 and O2 are reduced d. C6H12O6 is oxidized and O2 is reduced

D

In the reaction shown below Na and Cl → Na+ and Cl- Select one: a. Na and Cl are reduced b. Na is reduced and Cl is oxidized c. Na and Cl are oxidized d. Na is oxidized and Cl is reduced

D

In vertebrate animals, brown fat tissue's color is due to abundant blood vessels and capillaries. White fat tissue, on the other hand, is specialized for fat storage and contains relatively few blood vessels or capillaries. Brown fat cells have a specialized protein that dissipates the proton-motive force across the mitochondrial membranes. Which of the following might be the function of the brown fat tissue? Select one: a. to allow the animals to regulate their metabolic rate when it is especially hot b. to increase the production of ATP c. to allow other membranes of the cell to perform mitochondrial functions d. to regulate temperature by converting most of the energy from NADH oxidation to heat

D

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the Select one: a. affinity of oxygen for electrons. b. flow of electrons down the electron transport chain. c. oxidation of glucose and other organic compounds. d. H+ concentration across the membrane holding ATP synthase.

D

The process known as "substrate-level phosphorylation" Select one: a. occurs only during glycolysis b. occurs only during the citric acid cycle c. occurs only during oxidative phosphorylation d. occurs during both glycolysis and the citric acid cycle.

D

When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes Select one: a. dehydrogenated. b. oxidized. c. hydrolyzed. d. reduced.

D

When an electron moves from Select one: a. the first to the second subunit of the electron transport chain, energy is released that can be used to do work b. NADH to the first subunit of the electron transport chain, energy is released that can be used to do work c. the second to the third subunit of the electron transport chain, energy is released that can be used to do work d. all of these statements are true

D

When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the direct result is the Select one: a. lowering of pH in the mitochondrial matrix. b. formation of ATP. c. reduction of NAD+. d. creation of a proton-motive force.

D

Which of the following metabolic processes include glycolysis? Select one: a. fermentation b. aerobic respiration c. anaerobic respiration d. all of these answers are correct

D

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent? Select one: a. chemiosmosis b. oxidative phosphorylation c. electron transport d. glycolysis

D

Why are carbohydrates and fats considered high-energy foods? Select one: a. They are easily reduced. b. They have a lot of oxygen atoms. c. They can have very long carbon skeletons. d. They have a lot of electrons associated with hydrogen.

D

Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? Select one: a. The electrons have a higher potential energy when associated with water and CO2 than they do in organic compounds. b. The oxidation of organic compounds can be used to make ATP. c. The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. d. Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O).

D