Chapter 9 HW
In glycolysis there is a net gain of _____ ATP. a. 3 b. 1 c. 2 d. 4 e. 5
c
During acetyl CoA formation and the citric acid cycle, all of the carbon atoms that enter cellular respiration in the glucose molecule are released in the form of CO2. Use this diagram to track the carbon-containing compounds that play a role in these two stages. ***image*** Drag the labels from the left (which represent numbers of carbon atoms) onto the diagram to identify the number of carbon atoms in each intermediate in acetyl CoA formation and the citric acid cycle. Labels may be used more than once.
(a)2C, (b)6C, (c)6C, (d)5C, (e)4C, (f)4C, (g)4C, (h)4C, (i)4C
Each of the four stages of cellular respiration occurs in a specific location inside or outside the mitochondria. These locations permit precise regulation and partitioning of cellular resources to optimize the utilization of cellular energy. Match each stage of cellular respiration with the cellular location in which it occurs. Labels may be used once, more than once, or not at all. 1. Glycolysis: _____ 2. Acetyl CoA formation: _____ 3. Citric Acid cycle: _____ 4. Oxidative phosphorylation: _____
1. cytoplasm 2. mitochondrial matrix 3. mitochondrial matrix 4. inner mitochondrial membrane
Match each product of pyruvate metabolism with the condition under which it is produced. Drag each item to the appropriate bin. 1. lactate: _____ 2. ethanol: _____ 3. acetyl CoA: _____
1. fermentation in human muscle 2. fermentation in yeast and bacteria 3. aerobic oxidation
The ATP that is generated in glycolysis is produced by substrate-level phosphorylation, a very different mechanism than the one used to produce ATP during oxidative phosphorylation. Phosphorylation reactions involve the addition of a phosphate group to another molecule. Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis. 1. A bond must be broken between an organic molecule and phosphate before ATP can form. 2. One of the substrates is a molecule derived from the breakdown of glucose. 3. An enzyme is required in order for the reaction to occur. 4. The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions. 5. The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP.
Correct - 1, 2, 3 Incorrect: 4, 5
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
True
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
True
A typical eukaryotic cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen to an individual when they exhaust their ATP supply? a. Catabolic processes will be activated to generate additional ATP. b. ATP will be transported into the cells from the circulatory system. c. The athlete will have to sit down and rest. d. Anabolic processes will be activated to produce new mitochondria.
a
Approximately how much more free energy is supplied to the electron transport chain by NADH than by FADH2? a. 8 kcal/mol b. 45 kcal/mol c. 53 kcal/mol d. 98 kcal/mol e. They both feed electrons into Q, so there is no difference in free energy.
a
Energy released from the electron transport chain is used to pump H+ ions into which location in eukaryotic cells? a. mitochondrial intermembrane space b. mitochondrial matrix c. mitochondrial inner membrane d. cytoplasm adjacent to the mitochondrial outer membrane
a
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule? a. 2 NADH, 2 pyruvate, and 2 ATP b. 4 NADH, 2 pyruvate, and 4 ATP c. 6 CO2, 2 pyruvate, and 2 ATP d. 2 NAD+, 2 pyruvate, and 2 ATP
a
How will a healthy individual's ATP production change during an eight-hour fast? a. The individual's ATP production will not change significantly. b. The individual's ATP production will decrease significantly. c. The individual's ATP production will increase significantly.
a
Identify all correct statements about the basic function of fermentation. Select all that apply. a. The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis. b. The basic function of fermentation is the production of additional ATP by further oxidation of the products of glycolysis. c. The basic function of fermentation is the production of ethyl alcohol or lactic acid.
a
If a cell produces on average 30 ATP molecules for each molecule of glucose that is completely oxidized to carbon dioxide and water, how many ATP molecules on average can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water? a. 12.5 b. 25 c. 8 d. 14
a
In chemiosmosis, the most direct source of energy used to convert ADP + Pi to ATP is energy released ________. a. from movement of protons through ATP synthase, down their electrochemical gradient b. as electrons are transported across the inner mitochondrial membrane c. as electrons flow through the electron transport chain d. from substrate-level phosphorylation
a
In most cells, not all of the carbon compounds that participate in glycolysis and the citric acid cycle are converted to carbon dioxide by cellular respiration. What happens to the carbon in these compounds that does NOT end up as CO2? a. they are removed from these processes to serve as building blocks for other complex molecules b. they are used to make ATP from NADH c. they are used to convert ADP to ATP via chemiosmosis d. they are converted to heat energythey are used to make NADH
a
In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis? a. two ATP b. up to 30 ATP c. none, because all of the available energy remains in either lactate or ethanol d. none, because in the absence of oxygen no ATP can be made e. four ATP
a
Inhibition of which of the following processes would reduce or eliminate generation of a proton-motive force in mitochondria? a. pumping of hydrogen ions from the mitochondrial matrix across the inner membrane and into the intermembrane space b. the reduction of NAD+ by the first electron carrier in the electron transport chain c. lowering of pH in the mitochondrial matrix d. the flow of protons through ATP synthase down their concentration gradient
a
New biosensors, applied like a temporary tattoo to the skin, can alert endurance athletes that they are about to "hit the wall" and will find it difficult to continue exercising. These biosensors monitor lactate present in sweat during strenuous exercise. Which of the statements below best explains the use of lactate as an indicator of exercise capacity? a. 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. b. 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. c. During aerobic respiration, muscle cells cannot produce enough lactate to fuel muscle cell contractions, and muscles begin to cramp, thus athletic performance suffers. 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.
a
Select the correct statement about cellular respiration. a. Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level. b. Plants carry out cellular respiration only in organs such as roots that cannot carry out photosynthesis. c. Animals carry out cellular respiration whereas plants carry out photosynthesis.
a
The electrons stripped from glucose in cellular respiration ultimately end up in which compound? a. water b. ATP c. carbon dioxide d. NADH e. oxygen
a
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis. About 10% of Springer spaniels suffer from canine PFK deficiency. Dogs affected with this disorder most likely display which of the following symptoms? a. They are lethargic and readily tire from exercise. b. They carry out elevated levels of oxidative phosphorylation. c. They die as embryos. d. They constantly have low blood sugar.
a
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is a. O2. b. NAD+. c. water. d. pyruvate.
a
Under anaerobic conditions (a lack of oxygen), glycolysis continues in most cells despite the fact that oxidative phosphorylation stops, and its production of NAD+ (which is needed as an input to glycolysis) also stops. The diagram illustrates the process of fermentation, which is used by many cells in the absence of oxygen. In fermentation, the NADH produced by glycolysis is used to reduce the pyruvate produced by glycolysis to either lactate or ethanol. Fermentation results in a net production of 2 ATP per glucose molecule. *** During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. What would happen to the cell's rate of glucose utilization? a. Glucose utilization would increase a lot. b. Glucose utilization would increase a little. c. Glucose utilization would remain the same. d. Glucose utilization would decrease a little. e. Glucose utilization would decrease a lot.
a
What molecule is indicated by the letter D? a. oxygen b. water c. glucose d. ATP e. pyruvate
a
What molecules belong in space A and B? a. glucose and oxygen b. carbon dioxide and water c. oxygen and water d. carbon dioxide and oxygen e. glucose and carbon dioxide
a
What molecules belong in spaces E and F? a. carbon dioxide and water b. carbon dioxide and oxygen c. glucose, water, carbon dioxide, and oxygen d. oxygen and water e. glucose and oxygen
a
What process occurs within Box B? a. the citric acid cycle b. glycolysis c. oxidative phosphorylation d. electron transport e. photophosphorylation
a
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. NAD+ is oxidized. d. The electrons gain free energy.
a
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP? a. Glucose b. Phosphate c. ADP d. Carbon dioxide
a
Which of the following events takes place in the electron transport chain? a. the harnessing of energy from redox reactions to generate a proton gradient b. the breakdown of an acetyl group to carbon dioxide c. the breakdown of glucose into six carbon dioxide molecules d. substrate-level phosphorylation
a
Which of the following is true for most people? a. As you get older, your muscle mass decreases while the amount of collagen in your muscles increases. b. As you get older, your muscle mass increases as does the amount of collagen in your muscles. c. As you get older, your muscle mass increases while the amount of collagen in your muscles decreases. d. As you get older, your muscle mass decreases as does the amount of collagen in your muscles.
a
Which of the following is true of the energy levels of electrons in shells? a. Valence electrons have a higher energy level than those in other filled shells. b. All the electrons in an atom have similar energy levels. c. Electrons do not have potential energy, just kinetic energy. d. Electrons must lose energy to move from the first to the second shell.
a
Which of the following metabolic processes take place in the cytosol of a eukaryotic cell? a. glycolysis and fermentation b. citric acid cycle c. oxidation of pyruvate to acetyl CoA d. fermentation and chemiosmosis
a
Which of the following processes is driven by chemiosmosis? a. oxidative phosphorylation b. substrate-level phosphorylation c. ATP hydrolysis d. reduction of NAD+ to NADH
a
Which of the following statements best describes a characteristic of NAD+? a. NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle. b. NAD+ stores more chemical energy than NADH. c. NAD+ is oxidized in glycolysis to produce ATP. d. NAD+ may donate electrons for use in oxidative phosphorylation.
a
Which of the following statements best describes the primary role played by oxygen in cellular respiration? a. It serves as the final acceptor for electrons from the electron transport chain. b. It yields energy in the form of ATP as it is passed down the electron transport chain. c. It serves as an acceptor for carbon, forming CO2 in the citric acid cycle. d. It oxidizes glucose to form two molecules of pyruvate.
a
Which of the following statements describing the process of glycolysis is correct? a. It represents the first stage in the chemical oxidation of glucose by a cell. b. It requires ATP and NADH. c. It converts one glucose molecule to two molecules of pyruvate and carbon dioxide. d. Glycolysis produces 30 ATP from each molecule of glucose. e. Glycolysis occurs in the mitochondria.
a
Which of the following statements is not true of most cellular redox reactions? a. A hydrogen atom is transferred to the atom that loses an electron. b. The reactant that is oxidized loses electrons. c. The electron acceptor is reduced. d. Changes in potential energy can be released as heat.
a
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? a. Fermentation b. Electron transport chain c. Krebs cycle d. Glycolysis
a
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration? a. 18-24 b. 30-32 c. 2 d. 4
b
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal to form small vesicles that contain the intermembrane space. These vesicles can transfer electrons from NADH to oxygen and synthesize ATP. Which of the following statements best describes what will happen to the vesicles when NADH is added? a. Protons will be pumped out of the interior of the vesicle to the exterior using energy from ATP hydrolysis. b. The inside of the vesicles will become acidic. c. ATP will be produced from ADP and Pi in the interior of the vesicle. d. The inside of the vesicles will become alkaline.
b
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location than the active site. This is an example of which of the following? a. the specificity of enzymes for their substrates b. allosteric regulation c. positive feedback regulation d. competitive inhibition
b
In liver cells, the inner mitochondrial membranes contain about five times the surface area of the outer mitochondrial membranes, which allows for increased rates of which process below? a. substrate-level phosphorylation b. oxidative phosphorylation c. the citric acid cycle d. glycolysis
b
In muscle cells, fermentation produces _____. a. carbon dioxide, ethanol, NADH, and ATP b. lactate and NAD+ c. carbon dioxide, ethanol, and NAD+ d. pyruvate e. lactate, NADH, and ATP
b
In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. a. More ATP is produced per CO2 released in cyclic processes than in linear processes. b. It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA. c. Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes. d. Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis.
b
The synthesis of ATP by oxidative phosphorylation is an example of which of the following processes? a. active transport b. coupling of an endergonic reaction to an exergonic reaction c. a reaction with a positive ΔG d. allosteric regulation
b
Two molecules with the chemical formulas C6H12O6 and C6H12O2 are probably a. a nucleic acid and a fat b. a monosaccharide and a fatty acid c. a monosaccharide and a nucleotide d. a fat and a nucleotide
b
What is the correct order of electron transport compounds from best electron donor to best electron acceptor? a. NADH -- Cyt c -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt a of Complex IV-- O2 b. NADH -- Fe-S of Complex I -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV -- O2 c. O2 -- Cyt a of Complex IV -- Cyt c -- Fe-S of Complex III -- Q -- Fe-S of Complex I -- NADH d. O2 -- Fe-S of Complex I -- NADH -- Q -- Fe-S of Complex III -- Cyt c-- Cyt a of Complex IV
b
What organelle is indicated by the letter C? a. chloroplast b. mitochondrion c. peroxisome d. lysosome e. Golgi apparatus
b
What types of cells carry out ATP synthesis by chemiosmosis? a. only animal cells in mitochondria, exclusively using oxygen as the electron acceptor b. all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors c. all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor d. only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors
b
When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________. a. oxidized, and energy is released b. reduced, and energy is released c. reduced, and energy is used d. oxidized, and energy is used
b
Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule? a. reduction of pyruvate to lactate b. glycolysis c. the electron transport chain d. the citric acid cycle
b
Which of the following is one of the molecules formed by the removal of a carboxyl group (as CO2) from a molecule of pyruvate? a. water b. acetyl CoA c. ATP d. citrate
b
Which of the following is the most likely effect on the rates of ATP and CO2 production if yeast cells growing in minimal medium lacking glucose are provided with supplemental acetyl-CoA? *** a. The rates of ATP and carbon dioxide production would both decrease. 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. There would be no change in ATP production, but the rate of carbon dioxide production would increase.
b
Which of the following molecules is the lowest-energy donor of electrons to the electron transport chain? a. ATP b. FADH2 c. NADH d. water
b
Which of the following sequences describes the path by which electrons move from high-energy to lower-energy molecules in aerobic respiration? a. glucose → pyruvate → ATP → oxygen b. glucose → NADH → electron transport chain → oxygen c. glucose → pyruvate → electron transport chain → NADH → ATP d. food → glycolysis → citric acid cycle → NADH → ATP
b
Which of the following statements about the electron transport chain is true? a. Electrons gain energy as they move down the chain. b. NADH and FADH2 donate their electrons to the chain. c. The electron transport chain is the first step in cellular respiration. d. Water is the last electron acceptor.
b
Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration? a. The function of the citric acid cycle is the transfer of electrons from pyruvate to NADH to O2. b. The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP. c. The function of the bonding of acetic acid to the carrier molecule CoA to form acetyl CoA is the reduction of glucose to acetyl CoA.
b
Which of the following statements best describes the electron transport chain? a. It is driven by ATP hydrolysis. b. It consists of a series of redox reactions. c. It occurs in the cytoplasm of both prokaryotic and eukaryotic cells. d. It includes a series of hydrolysis reactions associated with mitochondrial membranes.
b
Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom? a. NAD+ becomes dehydrogenated. b. NAD+ becomes reduced. c. NAD+ becomes oxidized. d. NAD+ becomes ionized.
b
Which of the following statements best summarizes ATP use and production in the catabolism of each glucose molecule in glycolysis? a. four 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 four molecules of ATP are produced d. two molecules of ATP are used, and two molecules of ATP are produced
b
Which of these is NOT a product of the citric acid cycle? a. CO2 b. acetyl CoA c. ATP d. FADH2 e. NADH + H+
b
Which stage of glucose metabolism produces the most ATP? a. Krebs cycle b. Electron transport and chemiosmosis c. Fermentation of pyruvate to lactate d. Glycolysis
b
Which term describes the degree to which an element attracts electrons? a. Polarity. b. Electronegativity. c. Reduction. d. Oxidation.
b
You are a personal trainer, working to help your clients achieve optimum fitness in the least amount of time. Which of the following is most important for you to discuss with them to determine how intensely they should be working out? a. The amount of water they are consuming daily. b. Their maximum heart rate. c. The number of carbohydrates they are eating daily. d. The amount of sleep they are getting daily.
b
A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition? a. Its cells cannot complete glycolysis. b. Its cells cannot transport NADH from glycolysis into the mitochondria. c. Its cells cannot transport pyruvate from the cytosol into the mitochondria. d. Its cells have a defective electron transport chain, so glucose is metabolized to lactate instead of to acetyl CoA.
c
A person on a strict diet and exercise regimen lost 7 kg (about 15 pounds) of body fat in just two weeks. In which of the following forms did the lost fat most likely leave the body? a. converted to ATP, which weighs much less than fat b. converted to heat and then released c. released as CO2 and H2O d. eliminated from the body as feces
c
If a mitochondrion ran out of molecular oxygen (O2), predict which of the following situations would occur in its electron transport chain. a. FADH2 would be the main electron donor to the electron transport chain instead of NADH. b. H2O would be made instead of O2 at the end of the chain. c. FMN prosthetic groups would remain reduced and NADH would have nowhere to donate electrons. d. Cyt a 3 prosthetic groups would remain oxidized and Cyt a would have nowhere to donate electrons. e. Electrons would start to flow in the opposite direction, converting water into O2 and H+.
c
In cellular respiration, most ATP molecules are produced by _____. a. cellular respiration b. photosynthesis c. oxidative phosphorylation d. substrate-level phosphorylation e. photophosphorylation
c
In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the net production of which of the following sets of molecules? a. ATP, CO2, and acetyl CoA b. ATP, NADH, and ethanol c. ATP, CO2, and ethanol d. ATP, CO2, and lactate
c
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? a. ATP b. Water c. Carbon dioxide d. NADH
c
The enzyme phosphofructokinase (PFK) catalyzes a key step in glycolysis and is inhibited by high levels of which of the following molecules? a. citrate and CO2 b. glucose and NAD+ c. ATP and citrate d. AMP and ATP
c
The rate of cellular respiration is regulated by its major product, ATP, via feedback inhibition. As the diagram shows, high levels of ATP inhibit phosphofructokinase (PFK), an early enzyme in glycolysis. As a result, the rate of cellular respiration, and thus ATP production, decreases. Feedback inhibition enables cells to adjust their rate of cellular respiration to match their demand for ATP. Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production? a. ATP levels would rise at first, increasing the inhibition of PFK and increasing the rate of ATP production. b. ATP levels would fall at first, increasing the inhibition of PFK and increasing the rate of ATP production. c. ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production. d. ATP levels would rise at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
c
The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced? 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 process, 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
Under which conditions will plant cell mitochondria actively oxidize pyruvate and carry out oxidative phosphorylation? a. only in cells that store glucose in the form of starch and only in the dark b. in photosynthesizing cells in the light, and in other cells in the dark c. in all cells, with or without light d. only in photosynthetic cells in the light, while photosynthesis occurs concurrently
c
What is the oxidizing agent in the following reaction? Pyruvate+NADH+H+→Lactate+NAD+ a. NADH b. lactate c. pyruvate d. oxygen
c
What process occurs in Box A? a. oxidative phosphorylation b. electron transport and oxidative phosphorylation c. glycolysis d. electron transport e. the citric acid cycle
c
Which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle? *** a. 6 ATP, 6 CO2, 3 NADH, and 12 FADH2 b. 1 ATP, 2 CO2, 3 NADH, and 1 FADH2 c. 3 ATP, 6 CO2, 9 NADH, and 3 FADH2 d. 3 ATP, 3 CO2, 3 NADH, and 3 FADH2
c
Which of the following is the most correct interpretation of the figure? a. ADP + Pi are a set of molecules that store energy for catabolism. b. Energy from catabolism can be used directly for performing cellular work. c. ATP is a molecule that acts as an intermediary to store chemical energy for cellular work. d. Pi acts as a shuttle molecule to move energy from ATP to ADP.
c
Which of the following is the most important result of the process of cellular respiration in biological systems? a. the breakdown of glucose to carbon dioxide and water b. producing complex molecules from chemical building blocks c. transforming the energy in glucose and related molecules into a chemical form that cells can use for work d. breaking down ATP so that ADP and Pi can be reused e. catabolism of sugars and related compounds
c
Which of the following is true for all exergonic reactions? a. A net input of energy from the surroundings is required for the reactions to proceed. b. The reaction goes only in a forward direction: All reactants will be converted to products. c. The reaction proceeds with a net release of free energy. d. The products have more total energy than the reactants.
c
Which of the following statements about the chemiosmotic synthesis of ATP is correct? a. Chemiosmotic ATP synthesis requires oxygen. b. The chemiosmotic synthesis of ATP occurs only in eukaryotic cells, because it occurs in mitochondria. c. The chemiosmotic synthesis of ATP requires that electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane. d. The energy for production of ATP from ADP comes directly from a gradient of electrons across the inner mitochondrial membrane. e. Oxygen participates directly in the reaction that makes ATP from ADP and P.
c
Which of the following statements best explains why carbohydrates and fats may be considered high-energy foods? a. They contain many protons associated with oxygen atoms. b. They contain no low-energy nitrogen atoms. c. They contain many electrons associated with hydrogen atoms. d. They are strong oxidizing molecules.
c
Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation? a. reduction of FAD to FADH2 b. reduction of NAD+ to NADH c. oxidation of NADH to NAD+ d. hydrolysis of ATP to ADP + Pi
c
Which of the following statements is true of the bonds in a water molecule? a. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero. b. Oxygen acts as the electron acceptor and is oxidized. c. Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. d. The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1.
c
Which of the following types 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 reacts with NADH and oxidizes it to NAD+ c. an agent that closely mimics the structure of glucose but is not metabolized d. an agent that binds to pyruvate and inactivates it
c
Which of the summary statements below best describes the results of the following reaction? C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy a. CO2 is reduced and O2 is oxidized. b. O2 is reduced and CO2 is oxidized. c. C6H12O6 is oxidized and O2 is reduced. d. O2 is oxidized and H2O is reduced.
c
Which of these is NOT a product of glycolysis? a. NADH b. ATP c. FADH2 d. pyruvate
c
Which step of the cellular respiration pathway can take place in the absence of oxygen? a. Fermentation b. Krebs cycle c. Glycolysis d. Electron transport chain
c
Your 60-year-old aunt was recently diagnosed with sarcopenia. Which of the following activities will likely help her the most? a. running intervals b. CrossFit c. yoga d. biking intervals
c
Assuming the U.S. is similar to the U.K., which of the following will occur? a. More women will meet exercise recommendations, while men will not. b. More men will meet exercise recommendations, while women will not. c. More adults will meet exercise recommendations. d. There will be no real change in the exercise habits of adults in the coming years.
d
Beta oxidation generates substrates for cellular respiration through catabolism of which of the following molecules? a. glycogen b. proteins c. glucose d. fatty acids
d
Catabolism of fatty acids produces two-carbon molecules that are converted to acetyl CoA. The acetyl CoA molecules will most likely be metabolized in aerobic cellular respiration by which of the following mechanisms? a. directly entering the energy-yielding phase of glycolysis b. being converted to pyruvate and then undergo pyruvate oxidation upon transport into mitochondria c. directly entering the electron transport chain d. directly entering the citric acid cycle
d
Exposing inner mitochondrial membranes to ultrasonic vibrations will fragment the membranes and pieces will reseal "inside out" to form small vesicles. The fact that these vesicles can transfer electrons from NADH to oxygen and synthesize ATP suggests that which of the following components must be present? a. all of the electron transport system and the proteins that add CoA to acetyl groups b. only the electron transport system c. only the ATP synthase system d. all of the electron transport system and ATP synthase
d
Given what you know about glycolysis and regulation of metabolism by this enzyme, what is the mechanism by which phosphofructokinase activity differs depending on ATP concentration? a. Phosphofructokinase is an allosteric enzyme that is stimulated by AMP, ADP, and ATP. b. Phosphofructokinase is an allosteric enzyme that is inhibited by ADP and stimulated by ATP. c. Phosphofructokinase is an allosteric enzyme that is inhibited by AMP, ADP, and ATP. d. Phosphofructokinase is an allosteric enzyme that is inhibited by ATP and stimulated by AMP.
d
How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) a. Electron transport would be unaffected but ATP synthesis would stop. b. Electron transport would stop but ATP synthesis would be unaffected. c. Neither electron transport nor ATP synthesis would be affected. d. Both electron transport and ATP synthesis would stop.
d
If the proteins of the electron transport chain were labeled with a fluorescent tag, the fluorescence observed by microscopy will be localized to which of the following regions of the mitochondria? a. outer membrane b. matrix c. intermembrane space d. inner membrane
d
In glycolysis, ATP molecules are produced by _____. a. cellular respiration b. oxidative phosphorylation c. photosynthesis d. substrate-level phosphorylation e. photophosphorylation
d
In glycolysis, what starts the process of glucose oxidation? a. FADH2 b. hexokinase c. ADP d. ATP e. NADPH
d
In mitochondria, exergonic redox reactions a. are the source of energy driving prokaryotic ATP synthesis. b. reduce carbon atoms to carbon dioxide. c. are coupled via phosphorylated intermediates to endergonic processes. d. provide the energy that establishes the proton gradient.
d
In which reactions of cellular respiration 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
Inhibition of which of the following metabolic pathways would result in decreased rates of CO2 production? a. glycolysis and the oxidation of pyruvate to acetyl CoA b. oxidative phosphorylation and fermentation c. fermentation and glycolysis d. oxidation of pyruvate to acetyl CoA and the citric acid cycle
d
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? a. There is more NADH than FADH2 made for every glucose that enters cellular respiration. b. The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2. c. FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. d. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. e. It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH.
d
Of the following lists of electron transport compounds, which one lists them in order from the one containing electrons with the highest free energy to the one containing electrons with the lowest free energy? Note that not all electron transport compounds in the electron transport chain are listed. a. FADH2 -- Fe-S of Complex II -- Fe-S of Complex III -- Q -- Cyt a of Complex IV -- Cyt c -- O2 b. O2 -- Cyt a of Complex IV -- Cyt c -- Fe-S of Complex III -- Q -- Fe-S of Complex II -- FADH2 c. FMN of Complex I -- NADH -- Fe-S of Complex III -- Cyt b of Complex III -- Cyt c -- Cyt a of Complex IV -- O2 d. FADH2 -- Fe-S of Complex II -- Q -- Fe-S of Complex III -- Cyt c -- Cyt a of Complex IV -- O2
d
Recent research indicates which of the following? a. Those who exercise vigorously see more health benefits than those who exercise at a moderate pace. b. Intensity of exercise does not change how much time is needed to reap the benefits. c. Less time for exercise is needed if you exercise at a moderate intensity. d. Less time for exercise is needed if you exercise at a vigorous intensity.
d
Substrate-level phosphorylation accounts for approximately what percent of the ATP formed by the reactions of glycolysis? a. 2% b. 0% c. 38% d. 100%
d
Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation? a. ATP is needed to convert pyruvate to acetyl CoA. Without oxygen, no ATP can be made in oxidative phosphorylation. b. Oxygen is required to convert glucose to pyruvate in glycolysis. Without oxygen, no pyruvate can be made. c. Oxygen is an input to acetyl CoA formation. d. In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.
d
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? a. Redox. b. Polar covalent. c. Nonpolar covalent. d. Ionic.
d
What process occurs in structure H? a. cellular respiration b. intracellular digestion c. ribosome synthesis d. photosynthesis e. protein synthesis
d
When a cell is deprived of oxygen, which of the following processes will be inhibited first? a. the citric acid cycle b. the oxidation of pyruvate to acetyl CoA c. glycolysis d. the electron transport chain
d
When a glucose molecule loses a hydrogen atom in an oxidation-reduction reaction, the glucose molecule is ________. a. an oxidizing agent b. hydrolyzed c. reduced d. oxidized
d
Which of the following metabolic processes normally occurs in most cells regardless of oxygen (O2) availability? a. citric acid cycle b. lactate fermentation c. oxidative phosphorylation d. glycolysis
d
Which of the following statements about the citric acid cycle is correct? a. The citric acid cycle oxidizes glucose to carbon dioxide. b. The citric acid cycle depends on the availability of NAD+, which is a product of glycolysis. c. The oxidation of compounds by the citric acid cycle requires molecular oxygen. d. The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle. e. The citric acid cycle produces most of the ATP that is subsequently used by the electron transport chain.
d
Which of the following statements best describes how a reducing agent in is chemically altered in a biological redox reaction? a. It gains a hydrogen atom and loses potential energy. b. It loses a hydrogen atom and gains potential energy. c. It gains a hydrogen atom and gains potential energy. d. It loses a hydrogen atom and loses potential energy.
d
Which of the following statements best supports the claim that glycolysis is likely one of the first metabolic pathways to have evolved? a. It requires the presence of membrane-enclosed cell organelles found only in eukaryotic cells. b. It is present in prokaryotic cells but not in eukaryotic cells. c. It produces much less ATP than does oxidative phosphorylation. d. It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
d
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? a. Polar and nonpolar. b. Ionic and covalent. c. Proton and electron. d. Anion and cation.
d
Yeast cells with defective mitochondria that are incapable of performing cellular respiration will be able to survive by using which of the following molecules for energy? a. amino acids b. fatty acids c. cholesterol d. glucose
d
For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. a. 0 b. 2 c. 3 to 6 d. 3 e. 6
e
For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle. a. 5 b. 4 c. 1 d. 0 e. 2
e
Structure A is _____. *** a. sensory protein b. an electron donor c. an electron acceptor d. phospholipid e. ATP synthase
e
Which of these enters the citric acid cycle? a. glucose b. G3P c. NADH + H+ d. pyruvate e. acetyl CoA
e
Which one of the following statements about the redox reactions of the electron transport chain is correct? a. The oxidation of NADH is directly coupled to the reduction of oxygen to water. b. The electron transport chain takes electrons from water and gives them to oxygen. c. The redox reactions of the electron transport chain are directly coupled with the synthesis of ATP. d. NADH gains electrons in the initial reaction of the electron transport chain. e. The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.
e
Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? a. pyruvate and ATP only b. CO2 only c. ATP and NADH only d. O2 only e.ATP only f. NADH only g. pyruvate, ATP, and NADH
g
The four stages of cellular respiration do not function independently. Instead, they are coupled together because one or more outputs from one stage functions as an input to another stage. The coupling works in both directions, as indicated by the arrows in the diagram below. In this activity, you will identify the compounds that couple the stages of cellular respiration.***
image
In the last stage of cellular respiration, oxidative phosphorylation, all of the reduced electron carriers produced in the previous stages are oxidized by oxygen via the electron transport chain. The energy from this oxidation is stored in a form that is used by most other energy-requiring reactions in cells. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of oxidative phosphorylation.
net input: NADH, O2, ADP net output: NAD+, water, ATP not input or output: glucose, pyruvate, acetyl CoA, coenzyme A, CO2
In acetyl CoA formation, the carbon-containing compound from glycolysis is oxidized to produce acetyl CoA. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of acetyl CoA formation.
net input: coenzyme A, NAD+, pyruvate net output: NADH, CO2, acetyl CoA not input or output: O2, glucose, ADP, ATP
When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.)
remains the same: proton pumping rate, electron transport rate, rate of oxygen uptake decreases (or goes to zero): rate of ATP synthesis, size of the proton gradient increases: nothing
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose? a. oxidation of pyruvate to acetyl-CoA b. the citric acid cycle c. electron transport d. glycolysis
b
The proximate (immediate) source of energy for oxidative phosphorylation is _____. a. substrate-level phosphorylation b. ATP synthase c. ATP d. NADH and FADH2 e. kinetic energy that is released as hydrogen ions diffuse down their concentration gradient
e
A covalent bond is likely to be polar when a. one of the atoms sharing electrons is more electronegative than the other. b. the two atoms sharing electrons have the same electronegativity. c. the two atoms sharing electrons are the same elements. d. the two atoms sharing electrons are different elements.
a
A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happens to most of the energy that the cell obtains from the oxidation of glucose? a. it is stored in NADH and FADH2 b. it is lost as heat c. it is stored in the carbon dioxide and water molecules released by these processes d. it is stored in pyruvate e. It is stored in the ATP that was formed by glycolysis and the citric acid cycle.
a
In fermentation _____ is reduced and _____ is oxidized. a. pyruvate ... NADH b. lactate ... ethanol c. lactate ... NADH d. NAD+ ... pyruvate e. NADH ... lactate
a
How many NADH are produced by glycolysis? a. 3 b. 4 c. 1 d. 5 e. 2
e
Most CO2 from catabolism is released during a. the citric acid cycle. b. lactate fermentation. c. glycolysis. d. electron transport.
a
1. _____ is a multi-protein complex within the electron transport chain. 2. _____ is the final electron acceptor of the electron transport chain. 3. _____ is a nonprotein organic electron carrier within the electron transport chain. 4. _____ is a prosthetic group present in several components of the electron transport chain. 5. _____ donates electrons to the electron transport chain.
1. Complex III 2. O2 (molecular oxygen) 3. Q (ubiquinone) 4. Fe-S 5. NADH
Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation. Drag each item to the appropriate bin. 1. reactants: 2. products:
1. NADH & pyruvate 2. NAD+ & lactate
1. When a compound donates (loses) electrons, that compound becomes _____. Such a compound is often referred to as an electron donor. 2. When a compound accepts (gains) electrons, that compound becomes _____. Such a compound is often referred to as an electron acceptor. 3. In glycolysis, the carbon-containing compound that functions as the electron donor is _____. 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called _____. 5. _____ is the compound that functions as the electron acceptor in glycolysis. 6. The reduced form of the electron acceptor in glycolysis is _____.
1. oxidized 2. reduced 3. glucose 4. pyruvate 5. NAD+ 6. NADH
The final electron acceptor of cellular respiration is _____. a. oxygen b. CO2 c. NADH d. water e. FADH2
a
Considering this graph, under which condition is phosphofructokinase more active? a. Phosphofructokinase is more active at high ATP concentration. b. Phosphofructokinase is more active at low ATP concentration. c. Phosphofructokinase activity is the same at low and high ATPATP concentration.
b
If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA? a. 1/6 b. 1/3 c. 100% d. 2/3
b
If pyruvate oxidation is blocked, what is the most likely effect on the levels of oxaloacetate and citrate in the citric acid cycle shown in the accompanying figure? *** a. Both oxaloacetate and citrate will accumulate. b. Oxaloacetate will accumulate and citrate will decrease. c. Oxaloacetate will decrease and citrate will accumulate. d. Both oxaloacetate and citrate will decrease.
b
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the a. transfer of phosphate to ADP. b. H+ concentration gradient across the membrane holding ATP synthase. c. flow of electrons down the electron transport chain. d. oxidation of glucose and other organic compounds.
b
During electron transport, energy from _____ is used to pump hydrogen ions into the _____. a. acetyl CoA ... intermembrane space b. NADH ... intermembrane space c. NADH and FADH2 ... intermembrane space d. NADH and FADH2 ... mitochondrial matrix e. NADH ... mitochondrial matrix
c
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)? *** a. 32 b. 6 c. 4 d. 2
c
In cellular respiration, a series of molecules forming an electron transport chain alternately accepts and then donates electrons. What is the advantage of such an electron transport chain? a. The advantage of the respiratory electron transport chain is that oxygen is the final electron acceptor. b. The advantage of an electron transport chain is the production of a large number of reduced, high-energy intermediates. c. The advantage of an electron transport chain is that a small amount of energy is released with the transfer of an electron between each pair of intermediates.
c
In mitochondrial electron transport, what is the direct role of O2? a. to provide the driving force for the synthesis of ATP from ADP and Pi b. to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle c. to function as the final electron acceptor in the electron transport chain d. to provide the driving force for the production of a proton gradient
c
In the citric acid cycle, ATP molecules are produced by _____. a. oxidative phosphorylation b. photosynthesis c. substrate-level phosphorylation d. photophosphorylation e. cellular respiration
c
In the process of cellular respiration, what is consumed and what is produced? a. carbon dioxide is consumed and water is produced b. oxygen is consumed and glucose is produced c. glucose is consumed and carbon dioxide is produced d. ATP is consumed and oxygen is produced e. water is consumed and ATP is produced
c
Gaseous hydrogen burns in the presence of oxygen to form water:2H2 + O2 → 2H2O + energy. Which molecule is oxidized and what kind of bond is formed? a. Hydrogen, nonpolar. b. Oxygen, polar. c. Oxygen, nonpolar. d. Hydrogen, polar.
d
From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis.
net input: ADP, NAD+, glucose net output: NADH, ATP, pyruvate not input or output: CO2, acetyl CoA, coenzyme A, O2
In the citric acid cycle (also known as the Krebs cycle), acetyl CoA is completely oxidized. From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of the citric acid cycle.
net input: NAD+, acetyl CoA, ADP net output: NADH, ATP, coenzyme A, CO2 not input or output: O2, glucose, pyruvate
