Campbell Biology - Chapter 9
Which electron carrier(s) function in the citric acid cycle? A) NAD+ only B) NADH and FADH2 C) the electron transport chain D) ADP and ATP
B) NADH and FADH2
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is stored in the form of which of the following molecules? A) acetyl-CoA B) NAD+ C) pyruvate D) NADH
D) NADH
In which reactions of cellular respiration and fermentation does substrate-level phosphorylation occur? A) only in glycolysis B) only in the citric acid cycle C) only in the electron transport chain D) in both glycolysis and the citric acid cycle
D) in both glycolysis and the citric acid cycle
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules? A) ATP, CO2, and ethanol (ethyl alcohol) B) ATP, CO2, and lactate C) ATP, NADH, and ethanol D) ATP, CO2, and acetyl CoA
A) ATP, CO2, and ethanol (ethyl alcohol)
Which of the summary statements below describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A) C6H12O6 is oxidized and O2 is reduced. B) O2 is oxidized and H2O is reduced. C) CO2 is reduced and O2 is oxidized. D) O2 is reduced and CO2 is oxidized.
A) C6H12O6 is oxidized and O2 is reduced.
A young dog has never had much energy. He is brought to a veterinarian for help, and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition? A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane. B) His cells cannot move NADH from glycolysis into the mitochondria. C) His cells lack the enzyme in glycolysis that forms pyruvate. D) His cells have a defective electron transport chain, so glucose is metabolized to lactate instead of to acetyl CoA.
A) His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. What is the most likely way that the lost fat left the body? A) It was released as CO2 and H2O. B) It was converted to heat and then released. C) It was converted to ATP, which weighs much less than fat. D) It was eliminated from the body as feces.
A) It was released as CO2 and H2O.
Which of the following statements about NAD+ is true? A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle. B) NAD+ has more chemical energy than NADH. C) NAD+ can donate electrons for use in oxidative phosphorylation. D) In the absence of NAD+, glycolysis can still function.
A) NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements about these inside-out membrane vesicles is true? A) The inside of the vesicles will become acidic when NADH is added. B) The inside of the vesicles will become alkaline when NADH is added. C) ATP will be produced from ADP and Pi in the interior of the vesicle. D) The vesicles will pump protons out of the interior of the vesicle to the exterior using energy from ATP hydrolysis.
A) The inside of the vesicles will become acidic when NADH is added.
What happens when electrons are passed from one atom to a more electronegative atom? A) The more electronegative atom is reduced, and energy is released. B) The more electronegative atom is reduced, and energy is consumed. C) The more electronegative atom is oxidized, and energy is consumed. D) The more electronegative atom is oxidized, and energy is released.
A) The more electronegative atom is reduced, and energy is released.
When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs? A) The pH of the matrix increases. B) ATP synthase pumps protons by active transport. C) The electrons gain free energy. D) NAD+ is oxidized.
A) The pH of the matrix increases.
Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy? A) glucose B) cholesterol C) fatty acids D) amino acids
A) glucose
Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration? A) glucose → NADH → electron transport chain → oxygen B) glucose → pyruvate → ATP → oxygen C) glucose → pyruvate → electron transport chain → NADH → ATP D) food → glycolysis → citric acid cycle → NADH → ATP
A) glucose → NADH → electron transport chain → oxygen
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell? A) glycolysis and fermentation B) fermentation and chemiosmosis C) oxidation of pyruvate to acetyl CoA D) citric acid cycle
A) glycolysis and fermentation
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is A) oxygen. B) water. C) NAD+. D) pyruvate.
A) oxygen.
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated only by the reactions involved in oxidation of pyruvate to acetyl CoA? A) 1/6 B) 1/3 C) 2/3 D) all of it
B) 1/3
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? A) 8 B) 12.5 C) 16 D) 25
B) 12.5
Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products? A) 2 NAD+, 2 pyruvate, and 2 ATP B) 2 NADH, 2 pyruvate, and 2 ATP C) 4 NADH, 2 pyruvate, and 4 ATP D) 6 CO2, 2 pyruvate, and 2 ATP
B) 2 NADH, 2 pyruvate, and 2 ATP
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle? A) 2 B) 4 C) 6 D) 32
B) 4
A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply? A) He or she has to sit down and rest. B) Catabolic processes are activated that generate more ATP. C) ATP is transported into the cell from the circulatory system. D) Other cells take over, and the muscle cells that have used up their ATP cease to function.
B) Catabolic processes are activated that generate more ATP.
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise. Which of the statements below is the best explanation of why athletes would need to monitor lactate levels? A) During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions, and muscles begin to cramp, thus athletic performance suffers. B) During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration. C) During aerobic respiration, muscles cells produce too much lactate, which causes a rise in the pH of the muscle cells, thus athletes must consume increased amounts of sports drinks, high in electrolytes, to buffer the pH. D) During anaerobic respiration, muscle cells receive too little oxygen and begin to convert lactate to pyruvate (pyruvic acid), thus athletes experience cramping and fatigue.
B) During anaerobic respiration, lactate levels increase when muscles cells need more energy; however, muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
Why is glycolysis considered to be one of the first metabolic pathways to have evolved? A) It produces much less ATP than does oxidative phosphorylation. B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms. C) It is present in prokaryotic cells but not in eukaryotic cells. D) It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells.
B) It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction? A) It gains electrons and gains potential energy. B) It loses electrons and loses potential energy. C) It gains electrons and loses potential energy. D) It loses electrons and gains potential energy.
B) It loses electrons and loses potential energy.
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle? A) Oxaloacetate will decrease and citric acid will accumulate. B) Oxaloacetate will accumulate and citric acid will decrease. C) Both oxaloacetate and citric acid will decrease. D) Both oxaloacetate and citric acid will accumulate.
B) Oxaloacetate will accumulate and citric acid will decrease.
If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production? A) There would be no change in ATP production, but the rate of carbon dioxide production would increase. B) The rates of ATP production and carbon dioxide production would both increase. C) The rate of ATP production would increase, but the rate of carbon dioxide production would decrease. D) The rates of ATP and carbon dioxide production would both decrease.
B) The rates of ATP production and carbon dioxide production would both increase.
The oxygen consumed during cellular respiration is directly involved in which of the following processes or events? A) glycolysis B) accepting electrons at the end of the electron transport chain C) the citric acid cycle D) the oxidation of pyruvate to acetyl CoA
B) accepting electrons at the end of the electron transport chain
Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate? A) ATP B) acetyl CoA C) citrate D) water
B) acetyl CoA
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 ________. A) competitive inhibition B) allosteric regulation C) the specificity of enzymes for their substrates D) positive feedback regulation
B) allosteric regulation
Which of the following metabolic processes normally occurs regardless of whether or not oxygen (O2) is present? A) citric acid cycle B) glycolysis C) lactate fermentation D) oxidative phosphorylation
B) glycolysis
Where are the proteins of the electron transport chain located? A) mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix
B) mitochondrial inner membrane
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration? A) glycolysis and the oxidation of pyruvate to acetyl CoA B) oxidation of pyruvate to acetyl CoA and the citric acid cycle C) oxidative phosphorylation and fermentation D) fermentation and glycolysis
B) oxidation of pyruvate to acetyl CoA and the citric acid cycle
Which of the following processes is driven by chemiosmosis? A) substrate-level phosphorylation B) oxidative phosphorylation C) ATP hydrolysis D) reduction of NAD+ to NADH
B) oxidative phosphorylation
In mitochondria, exergonic redox reactions A) are the source of energy driving prokaryotic ATP synthesis. B) provide the energy that establishes the proton gradient. C) reduce carbon atoms to carbon dioxide. D) are coupled via phosphorylated intermediates to endergonic processes.
B) provide the energy that establishes the proton gradient.
Most CO2 from catabolism is released during A) glycolysis. B) the citric acid cycle. C) lactate fermentation. D) electron transport.
B) the citric acid cycle.
In glycolysis, for each molecule of glucose oxidized to pyruvate, ________. A) two molecules of ATP are used, and two molecules of ATP are produced B) two molecules of ATP are used, and four molecules of ATP are produced C) four molecules of ATP are used, and two molecules of ATP are produced D) two molecules of ATP are used, and six molecules of ATP are produced
B) two molecules of ATP are used, and four molecules of ATP are produced
Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle? A) 1 ATP, 2 CO2, 3 NADH, and 1 FADH2 B) 3 ATP, 3 CO2, 3 NADH, and 3 FADH2 C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2 D) 6 ATP, 6 CO2, 3 NADH, and 12 FADH2
C) 3 ATP, 6 CO2, 9 NADH, and 3 FADH2
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. PFK is inhibited by high levels of which of the following molecules? A) glucose and NAD+ B) AMP and ATP C) ATP and citrate D) citrate and CO2
C) ATP and citrate
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the A) oxidation of glucose and other organic compounds. B) flow of electrons down the electron transport chain. C) H+ concentration gradient across the membrane holding ATP synthase. D) transfer of phosphate to ADP.
C) H+ concentration gradient across the membrane holding ATP synthase.
Which of the following statements about the electron transport chain is true? A) It is driven by ATP hydrolysis. B) It includes a series of hydrolysis reactions associated with mitochondrial membranes. C) It consists of a series of redox reactions D) It occurs in the cytoplasm of both prokaryotic and eukaryotic cells.
C) It consists of a series of redox reactions
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve? A) It allows for an increased rate of glycolysis. B) It allows for an increased rate of the citric acid cycle. C) It increases the surface for oxidative phosphorylation. D) It increases the surface for substrate-level phosphorylation.
C) It increases the surface for oxidative phosphorylation.
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol, and the free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed? A) Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis. B) Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat. C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis. D) There is no CO2 or water produced as products of glycolysis.
C) Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
What happens to a glucose molecule when it loses a hydrogen atom as the result of an oxidation-reduction reaction? A) The glucose molecule is hydrolyzed. B) The glucose molecule is an oxidizing agent. C) The glucose molecule is oxidized. D) The glucose molecule is reduced.
C) The glucose molecule is oxidized.
Why are carbohydrates and fats frequently considered high-energy foods? A) They contain many oxygen atoms. B) They contain no nitrogen atoms. C) They contain many electrons associated with hydrogen atoms. D) They are strong oxidizing molecules.
C) They contain many electrons associated with hydrogen atoms.
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Given its critical role in glycolysis, which of the following conditions would be a likely consequence for dogs afflicted with this disorder? A) They would die as embryos. B) They would have elevated blood-glucose levels, which may result in a high incidence of diabetes. C) They would be lethargic and readily tire from exercise. D) They would carry out elevated levels of oxidative phosphorylation.
C) They would be lethargic and readily tire from exercise.
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. Which of the following sets of products result from these reactions? A) acetyl CoA, O2, and ATP B) acetyl CoA, FADH2, and CO2 C) acetyl CoA, NADH, and CO2 D) acetyl CoA, NAD+, ATP, and CO2
C) acetyl CoA, NADH, and CO2
Which kind of metabolic poison would most directly interfere with glycolysis? A) an agent that reacts with oxygen and depletes its concentration in the cell B) an agent that binds to pyruvate and inactivates it C) an agent that closely mimics the structure of glucose but is not metabolized D) an agent that reacts with NADH and oxidizes it to NAD+
C) an agent that closely mimics the structure of glucose but is not metabolized
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + Pi to ATP? A) energy released as electrons flow through the electron transport chain B) energy released from substrate-level phosphorylation C) energy released from movement of protons through ATP synthase, down their electrochemical gradient D) energy released as electrons are transported across the inner mitochondrial membrane
C) energy released from movement of protons through ATP synthase, down their electrochemical gradient
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? A) the citric acid cycle B) the electron transport chain C) glycolysis D) reduction of pyruvate to lactate
C) glycolysis
Even though plants cells carry out photosynthesis, they still use their mitochondria for oxidation of pyruvate. Under what conditions will plant cell mitochondria be active in this process? A) only in photosynthetic cells in the light, while photosynthesis occurs concurrently B) only in cells that store glucose in the form of starch and only in the dark C) in all cells, with or without light D) in photosynthesizing cells in the light, and in other cells in the dark
C) in all cells, with or without light
Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? A) cytoplasm adjacent to the mitochondrial outer membrane B) mitochondrial inner membrane C) mitochondrial intermembrane space D) mitochondrial matrix
C) mitochondrial intermembrane space
Water is one of the end products of aerobic respiration. What is the source of the oxygen atom used in formation of the water? A) carbon dioxide (CO2) B) glucose (C6H12O6) C) molecular oxygen (O2) D) pyruvate (C3H3O3-)
C) molecular oxygen (O2)
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation? A) reduction of NAD+ to NADH B) reduction of FAD to FADH2 C) oxidation of NADH to NAD+ D) hydrolysis of ATP to ADP + Pi
C) oxidation of NADH to NAD+
When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes ________. A) dehydrogenated B) oxidized C) reduced D) redoxed
C) reduced
Which of the following events takes place in the electron transport chain? A) the breakdown of glucose into six carbon dioxide molecules B) the breakdown of an acetyl group to carbon dioxide C) the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle D) substrate-level phosphorylation
C) the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis? A) 0% B) 2% C) 38% D) 100%
D) 100%
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? A) 2 B) 4 C) 18-24 D) 30-32
D) 30-32
During aerobic respiration, which of the following molecules directly donates electrons to the electron transport chain at the lowest energy level? A) NADH B) ATP C) water D) FADH2
D) FADH2
An organism is discovered that thrives in both the presence and absence of oxygen. Interestingly, as oxygen is removed from the organism's environment, the rate of sugar consumption increases while the growth rate decreases. What do these observations suggest about the likely identity of this organism? A) It is an unremarkable eukaryotic organism. B) It is a photosynthetic organism. C) It is an obligate anaerobic organism. D) It is a facultative anaerobic organism.
D) It is a facultative anaerobic organism.
Which of the following statements best describes the primary role played by oxygen in cellular respiration? A) It yields energy in the form of ATP as it is passed down the electron transport chain. B) It oxidizes glucose to form two molecules of pyruvate. C) It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. D) It serves as the final acceptor for electrons from the electron transport chain.
D) It serves as the final acceptor for electrons from the electron transport chain.
Fatty acids usually have an even number of carbons in their structures. Catabolism of fatty acids produces two-carbon fragments that are converted to acetyl CoA molecules. What is the most likely way in which these acetyl CoA molecules would be metabolized in aerobic cellular respiration? A) They would directly enter the electron transport chain. B) They would directly enter the energy-yielding phase of glycolysis. C) They would be converted to pyruvate and then undergo pyruvate oxidation upon transport into mitochondria. D) They would directly enter the citric acid cycle.
D) They would directly enter the citric acid cycle.
Exposing inner mitochondrial membranes to ultrasonic vibrations will disrupt the membranes. However, the fragments will reseal "inside out." The little vesicles that result can still transfer electrons from NADH to oxygen and synthesize ATP. After the disruption, which components involved in oxidative phosphorylation must be present for electron transfer and ATP synthesis to still occur? A) only the electron transport system B) only the ATP synthase system C) all of the electron transport system and the proteins that add CoA to acetyl groups D) all of the electron transport system and ATP synthase
D) all of the electron transport system and ATP synthase
What kinds of cells carry out ATP synthesis by chemiosmosis? A) all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor B) only animal cells in mitochondria, exclusively using oxygen as the electron acceptor C) only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
D) all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
Beta oxidation generates substrates for cellular respiration through which of the following processes? A) catabolism of glucose B) catabolism of glycogen C) catabolism of proteins D) catabolism of fatty acids
D) catabolism of fatty acids
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 which of the following processes? A) active transport B) allosteric regulation C) a reaction with a positive ΔG D) coupling of an endergonic reaction to an exergonic reaction
D) coupling of an endergonic reaction to an exergonic reaction
Which of the following processes generates a proton-motive force in mitochondria? A) the flow of protons through ATP synthase down their concentration gradient B) the reduction of NAD+ by the first electron carrier in the electron transport chain C) lowering of pH in the mitochondrial matrix D) pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space
D) pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ → Lactate + NAD+ A) NADH B) NAD+ C) lactate D) pyruvate
D) pyruvate
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H- Lactate + NAD- A) oxygen B) NADH C) lactate D) pyruvate
D) pyruvate
During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released? A) glycolysis B) electron transport C) oxidation of pyruvate to acetyl-CoA D) the citric acid cycle
D) the citric acid cycle