Mastering Biology: Chapter 9

25 July 2022
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question
The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the
answer
H+ concentration across the membrane holding ATP synthase.
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Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?
answer
glycolysis
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What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ ? Lactate + NAD+
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pyruvate
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When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?
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The pH of the matrix increases.
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Most CO2 from catabolism is released during
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the citric acid cycle.
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Select the correct statement about cellular respiration.
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Cellular respiration and breathing differ in that cellular respiration is at the cellular level, whereas breathing is at the organismal level.
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How will a healthy individual's ATP production change during an eight-hour fast?
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The individual's ATP production will not change significantly.
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Which of the following statements accurately describes the function of a metabolic pathway involved in cellular respiration?
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The function of glycolysis is to begin catabolism by breaking glucose into two molecules of pyruvate, with a net yield of two ATP.
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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?
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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.
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Identify all correct statements about the basic function of fermentation. Select all that apply.
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The basic function of fermentation is the regeneration of NAD+, which allows continued ATP production by glycolysis.
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Which of the following cheeses would likely spoil the most quickly?
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A low fat, low salt variety.
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You create a new variety of cheese that has very little water. Which of the following is true?
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It is quite high in fat.
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You are a cheese maker wanting to connect a large quantity of lactose to acid. Which of the following do you need?
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bacteria
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Successfully making cheese requires separating what?
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curds and whey
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Which of the following is true?
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A high fat cheese is less dense than a low fat cheese.
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Based on the graph, is PFK more active at low or high ATP concentration?
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PFK is more active at low ATP concentration.
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Given what you know about glycolysis and regulation of metabolism by PFK, what is the likely mechanism by which PFK activity differs depending on ATP concentration?
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PFK is an allosteric enzyme that is inhibited by ATP and stimulated by AMP.
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In mitochondria, exergonic redox reactions
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provide the energy that establishes the proton gradient.
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The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
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oxygen.
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What process occurs in structure H?
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photosynthesis
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What molecules belong in space A and B?
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glucose and oxygen
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What organelle is indicated by the letter C?
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mitochondrion
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What molecules belong in spaces E and F?
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carbon dioxide and water
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What process occurs in Box A?
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glycolysis
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What process occurs within Box B?
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the citric acid cycle
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What molecule is indicated by the letter D?
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oxygen
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Which term describes the degree to which an element attracts electrons?
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Electronegativity.
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Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
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Anion and cation.
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Which of the following statements is true of the bonds in a water molecule?
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Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.
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Which of the following statements is not true of most cellular redox reactions?
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A hydrogen atom is transferred to the atom that loses an electron.
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What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
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Ionic
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Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 ? 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?
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Hydrogen, polar.
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Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration?
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transforming the energy in glucose and related molecules in a chemical form that cells can use for work
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In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?
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Glucose is consumed, and carbon dioxide is produced.
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Substrate-level phosphorylation occurs _____.
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in both glycolysis and the citric acid cycle
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The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction _____.
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loses electrons and loses potential energy
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When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____.
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reduced, and energy is released
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Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 ? 6 CO2 + 6 H2O + Energy
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C6H12O6 is oxidized and O2 is reduced.
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When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.
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oxidized
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When a molecule of NAD+ (nicotinamide adenine dinucleotide) gains a hydrogen atom (not a proton), the molecule becomes _____.
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reduced
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Which of the following statements about NAD+ is true?
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NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
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The oxygen consumed during cellular respiration is involved directly in which process or event?
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accepting electrons at the end of the electron transport chain
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Carbohydrates and fats are considered high-energy foods because they _____.
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have a lot of electrons associated with hydrogen.
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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?
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Catabolic processes are activated that generate more ATP.
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In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox, reactions. Drag the words on the left to the appropriate blanks on the right to complete the sentences.
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*oxidized reduced glucose pyruvate NAD+ NADH
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Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?
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pyruvate, ATP, and NADH
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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.
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*In substrate-level phosphorylation, an enzyme transfers a phosphate group from one molecule (an intermediate in the breakdown of glucose to pyruvate) to ADP to form ATP. This is very different from the mechanism of ATP synthesis that takes place in oxidative phosphorylation.
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How many NADH are produced by glycolysis?
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2
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In glycolysis, ATP molecules are produced by _____.
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substrate-level phosphorylation
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Which of these is NOT a product of glycolysis?
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FADH2
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In glycolysis, what starts the process of glucose oxidation?
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ATP
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In glycolysis there is a net gain of _____ ATP.
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2
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Which of the following describes the process of glycolysis?
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It represents the first stage in the chemical oxidation of glucose by a cell.
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Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
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100%
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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?
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Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
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Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.
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2 NADH, 2 pyruvate, and 2 ATP
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In glycolysis, for each molecule of glucose oxidized to pyruvate _____.
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two molecules of ATP are used and four molecules of ATP are produced.
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Which kind of metabolic poison would most directly interfere with glycolysis?
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an agent that closely mimics the structure of glucose but is not metabolized
question
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. 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.
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a-2 b-6 c-6 d-5 e-4 f-4 g-4 h-4 i-4
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In the sequential reactions of acetyl CoA formation and the citric acid cycle, pyruvate (the output from glycolysis) is completely oxidized, and the electrons produced from this oxidation are passed on to two types of electron acceptors. Drag the labels on the left to show the net redox reaction in acetyl CoA formation and the citric acid cycle. Note that two types of electron carriers are involved.
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a. CO2 b. NADH c. FAD d. FADH2
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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.
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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.
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Which of these enters the citric acid cycle?
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acetyl CoA
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In the citric acid cycle, ATP molecules are produced by _____.
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substrate-level phosphorylation
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Which of these is NOT a product of the citric acid cycle?
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acetyl CoA
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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 happened to most of the energy that the cell obtains from the oxidation of glucose?
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It is stored in NADH and FADH2
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Which statement about the citric acid cycle is correct?
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The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
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Most of the CO2 from the catabolism of glucose is released during _____.
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the citric acid cycle
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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 in the form of _____.
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NADH
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Which electron carrier(s) function in the citric acid cycle?
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NADH and FADH2
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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?
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The rates of ATP production and carbon dioxide production would both increase.
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Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
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oxidation of pyruvate to acetyl CoA and the citric acid cycle
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If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle?
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2/3
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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)?
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4
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If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
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Oxaloacetate will accumulate and citric acid will decrease.
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Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)?
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3 ATP, 6 CO2, 9 NADH, and 3 FADH2
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Use the following information to answer the questions below. 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. The three listed steps result in the formation of _____.
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acetyl CoA, NADH, and CO2
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Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?
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acetyl CoA
question
From the following compounds involved in cellular respiration, choose those that are the net inputs and net outputs of glycolysis. Drag each compound to the appropriate bin. If the compound is not involved in glycolysis, drag it to the "not input or output" bin.
answer
*In glycolysis, the six-carbon sugar glucose is converted to two molecules of pyruvate (three carbons each), with the net production of 2 ATP and 2 NADH per glucose molecule. There is no O2 uptake or CO2 release in glycolysis.
question
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. Drag each compound to the appropriate bin. If a compound is not involved in acetyl CoA formation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of acetyl CoA formation are included.)
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*In acetyl CoA formation, pyruvate (a product of glycolysis) is oxidized to acetyl CoA, with the reduction of NAD+ to NADH and the release of one molecule of CO2.
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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. Drag each compound to the appropriate bin. If a compound is not involved in the citric acid cycle, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of the citric acid cycle are included.)
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*In the citric acid cycle, the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. In addition, one molecule of ATP is produced.
question
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. Drag each compound to the appropriate bin. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.)
answer
*In oxidative phosphorylation, the NADH and FADH2 produced by the first three stages of cellular respiration are oxidized in the electron transport chain, reducing O2 to water and recycling NAD+ and FAD back to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production.
question
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.
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cytosol mitochondrial matrix mitochodrial matrix inner mitochondrial membrane
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In mitochondrial electron transport, what is the direct role of O2?
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to function as the final electron acceptor in the electron transport chain
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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.)
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Both electron transport and ATP synthesis would stop.
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Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
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Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.
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Sort the labels into the correct bin according to the effect that gramicidin would have on each process.
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*Gramicidin causes membranes to become very leaky to protons, so that a proton gradient cannot be maintained and ATP synthesis stops. However, the leakiness of the membrane has no effect on the ability of electron transport to pump protons. Thus, the rates of proton pumping, electron transport, and oxygen uptake remain unchanged.
question
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. Drag the labels on the left onto the diagram to identify the compounds that couple each stage. Labels may be used once, more than once, or not at all.
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a. pyruvate b. NADH c. NAD+ d. NADH e. NAD+
question
Which of these statements is the correct explanation for this observation?
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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.
question
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. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?
answer
ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.
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What would happen to the cell's rate of glucose utilization?
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Glucose utilization would increase a lot.
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Which molecule is metabolized in a cell to produce energy for performing work?
answer
Glucose
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True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
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T
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Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
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Fermentation
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Which step of the cellular respiration pathway can take place in the absence of oxygen?
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Glycolysis
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Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
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Carbon dioxide
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Which of the following statements about the electron transport chain is true?
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NADH and FADH2 donate their electrons to the chain.
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Which stage of glucose metabolism produces the most ATP?
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Electron transport and chemiosmosis
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True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
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True
question
The electrons stripped from glucose in cellular respiration end up in which compound?
answer
The electrons stripped from glucose in cellular respiration end up in which compound?
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Which of the following statements about the chemiosmotic synthesis of ATP is correct?
answer
The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.
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Which one of the following statements about the redox reactions of the electron transport chain is correct?
answer
The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.
question
To see patterns in the data from an experiment like this, it is helpful to graph the data. A bar graph is used instead of a line graph because each type of liver cell was independent of the others. But first, you must determine which variable should go on each axis of the graph. What variable did the researchers intentionally vary in the experiment, and what are the units for this variable?
answer
thyroid hormone level of the rats chosen for the experiment, in relative units
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What variable responded to thyroid hormone level (the independent variable), and what are the units for this variable?
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Thyroid hormone level is the independent variable, which goes on the x-axis.
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What variable responded to thyroid hormone level (the independent variable), and what are the units for this variable?
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oxygen consumption rate of liver cells, in nmol O2/min • mg cells
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Now that you have determined which variable goes on each axis, the graph can be constructed. Assuming that the x-axis tick marks will be used to identify the thyroid hormone level of each type of rat, what bars should appear on the x-axis?
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Low, Normal, Elevated
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Assuming that the y-axis tick marks will be separated by 1.0 (0.0, 1.0, 2.0, and so on), what is the largest value that should appear on the y-axis?
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9.0
question
Which cell type(s) had the highest rate of oxygen consumption?
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cells from rats with elevated thyroid hormone
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Which cell type(s) had the lowest rate of oxygen consumption?
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cells from rats with low thyroid hormone
question
Do the results in the graph support the researchers' hypothesis?
answer
Yes; cells that were exposed to elevated thyroid hormone levels showed increased oxygen consumption, indicating that the efficiency of the electron transport chain was reduced.
question
Based on what you know about mitochondrial electron transport and heat production, predict which rats had the highest body temperature, and which had the lowest body temperature.
answer
Rats with elevated thyroid hormone had the highest body temperature; rats with low thyroid hormone had the lowest.
question
Which of the following events takes place in the electron transport chain?
answer
the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle
question
The electron transport chain _____.
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is a series of redox reactions
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The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.
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how ATP is synthesized by a proton motive force
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During aerobic respiration, electrons travel downhill in which sequence?
answer
glucose ? NADH ? electron transport chain ? oxygen
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Where are the proteins of the electron transport chain located?
answer
mitochondrial inner membrane
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During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
answer
FADH2
question
The primary role of oxygen in cellular respiration is to _____.
answer
act as an acceptor for electrons and hydrogen, forming water
question
During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?
answer
molecular oxygen (O2)
question
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + i to ATP?
answer
energy released from movement of protons through ATP synthase, down their electrochemical gradient
question
Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
answer
mitochondrial intermembrane space
question
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.
answer
creation of a proton-motive force
question
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
answer
30-32
question
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 _____.
answer
an endergonic reaction coupled to an exergonic reaction
question
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?
answer
14
question
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
answer
It increases the surface for oxidative phosphorylation.
question
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 his body?
answer
It was released as CO2 and H2O.
question
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, when electron transfer and ATP synthesis still occur, what must be present?
answer
all of the electron transport proteins and ATP synthase
question
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. These inside-out membrane vesicles will _____.
answer
become acidic inside the vesicles when NADH is added
question
Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____.
answer
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
question
Match each product of pyruvate metabolism with the condition under which it is produced.
answer
*In the presence of oxygen, human cells carry out aerobic respiration, which yields acetyl CoA. In the absence of oxygen, human cells can carry out lactic acid fermentation, which yields lactate. Yeasts and many bacteria carry out alcohol fermentation, which takes place under anaerobic conditions, and produces ethanol.
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In muscle cells, fermentation produces _____.
answer
lactate and NAD+
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In fermentation _____ is reduced and _____ is oxidized.
answer
pyruvate ... NADH
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In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?
answer
two ATP
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Which of the following normally occurs regardless of whether or not oxygen (O2) is present?
answer
glycolysis
question
Which of the following occurs in the cytosol of a eukaryotic cell?
answer
glycolysis and fermentation
question
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____.
answer
ATP, CO2, and ethanol (ethyl alcohol)
question
One function of both alcohol fermentation and lactic acid fermentation is to _____.
answer
oxidize NADH to NAD+
question
An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____.
answer
is a facultative anaerobe
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Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
answer
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
question
Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
answer
glucose
question
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and 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?
answer
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.
question
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?
answer
The carbon compounds are removed from these processes to serve as building blocks for other complex molecules.
question
What is the oxidizing agent in the following reaction? Pyruvate + NADH + H+ ? Lactate + NAD+
answer
pyruvate
question
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 _____.
answer
allosteric regulation
question
Glycolysis is active when cellular energy levels are _____; the regulatory enzyme, phosphofructokinase, is _____ by ATP.
answer
low; inhibited
question
Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an estimated 10% of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is _____.
answer
an intolerance for exercise
question
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?
answer
His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
question
Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____.
answer
all cells all the time
question
In respiration, beta oxidation involves the _____.
answer
breakdown of fatty acids
question
Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules. These acetyl groups _____.
answer
directly enter the citric acid cycle
question
Cellular respiration requires fuel (glucose) and oxygen gas. The main process that produces these inputs is _____.
answer
photosynthesis
question
Which part(s) of cellular respiration require(s) oxygen gas?
answer
the Citric Acid cycle the electron transport chain
question
What is/are the most important output(s) of glycolysis?
answer
two pyruvic acid and two NADH molecules
question
Unlike the Citric Acid cycle and electron transport, glycolysis occurs _____.
answer
in the cytoplasm
question
Glycolysis is the multi-step breakdown of _____. Several different _____ play a role in this process.
answer
glucose ... enzymes
question
A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to kill bacteria in people with infections. However, he cannot do this because __________.
answer
human cells must also perform glycolysis; the drug might also poison them
question
Fermentation is essentially glycolysis plus an extra step in which pyruvate is reduced to form lactate or alcohol and carbon dioxide. This last step __________.
answer
enables the cell to recycle the reduced NADH to oxidized NAD+
question
A small amount of ATP is made in glycolysis by which of the following processes?
answer
transfer of a phosphate group from a fragment of glucose to ADP by substrate-level phosphorylation
question
Drag the labels onto the diagram to identify how chemicals cycle in an ecosystem.
answer
gas we exhale: CO2 water: H2O food that plats produce: glucose gas produced by photosynthesis: O2
question
When a poison such as cyanide blocks the electron transport chain, glycolysis and the citric acid cycle also eventually stop working. Which of the following is the best explanation for this?
answer
NAD+ and FAD are not available for glycolysis and the citric acid cycle to continue.
question
Which part(s) of cellular respiration take(s) place in the mitochondria?
answer
the Citric Acid cycle and the electron transport chain
question
What is the role of oxygen in cellular respiration?
answer
Oxygen accepts high-energy electrons after they are stripped from glucose.
question
Cellular respiration accomplishes two major processes: (1) it breaks glucose down into smaller molecules, and (2) it harvests the chemical energy released and stores it in ATP molecules. By the end of _____, the breakdown of glucose is complete; most ATP molecules are produced during _____.
answer
the Citric Acid cycle ... electron transport
question
NADH and FADH 2 are important in cellular respiration because they deliver high-energy electrons to the electron transport system. Electron transport produces _____ ATP molecule(s) per NADH molecule and _____ ATP molecules(s) per FADH 2 molecule.
answer
three ... two
question
In electron transport, high-energy electrons "fall" to oxygen through a series of reactions. The energy released is used to _____.
answer
transport protons into the intermembrane space of the mitochondria, where they become concentrated. They then flow back out into the the inner compartment (matrix) of the mitochodria. On the way back, protons turn ATP synthase turbines and produce ATP.
question
Select the correct sequence of steps as energy is extracted from glucose during cellular respiration.
answer
glycolysis ? acetyl CoA ? citric acid cycle ? electron transport chain
question
What is the correct general equation for cellular respiration?
answer
C6H12O6 + 6 O2 ? 6 CO2 + 6 H2O + ATP energy
question
Which of the following processes takes place in the cytosol of a eukaryotic cell?
answer
glycolysis
question
In what organelle would you find acetyl CoA formation, the citric acid cycle, and the electron transport chain?
answer
mitochondrion
question
Which statement describes glycolysis?
answer
This process splits glucose in half and produces 2 ATPs for each glucose.
question
Which statement describes the electron transport chain?
answer
This process uses energy captured from electrons flowing to oxygen to produce most of the ATPs in cellular respiration.
question
Which of the following molecules is broken down in cellular respiration, providing fuel for the cell?
answer
glucose
question
Which energy-rich molecule produced by cellular respiration directly powers cell work?
answer
ATP
question
How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?
answer
4
question
A molecule becomes more oxidized when it __________.
answer
loses an electron
question
Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of which of the following compounds?
answer
lactate
question
Where do the reactions of glycolysis occur in a eukaryotic cell?
answer
the cytosol
question
Which of the following events accompanies the conversion of pyruvate to acetyl CoA before the citric acid cycle?
answer
release of CO2 and synthesis of NADH
question
There is no production of carbon dioxide in glycolysis. Which of the following is the best explanation for this fact?
answer
The products of glycolysis contain the same total number of carbon atoms as in the starting material.
question
The function of cellular respiration is to __________.
answer
extract usable energy from glucose
question
Which of the following best describes the electron transport chain?
answer
Electrons are passed from one carrier to another, releasing a little energy at each step.
question
In the overall process of glycolysis and cellular respiration, __________ is oxidized and __________ is reduced.
answer
glucose ... oxygen
question
In preparing pyruvate to enter the citric acid cycle, which of the following steps occurs?
answer
Pyruvate is oxidized and a molecule of carbon dioxide is removed. The electrons removed in this process are used to reduce NAD+ to NADH.
question
Each ATP molecule contains about 1% of the amount of chemical energy available from the complete oxidation of a single glucose molecule. Cellular respiration produces about 32 ATP from one glucose molecule. What happens to the rest of the energy in glucose?
answer
It is converted to heat.
question
Which of the following is a correct description of the events of cellular respiration in proper sequence?
answer
oxidation of glucose to pyruvate; oxidation of pyruvate; citric acid cycle; oxidative phosphorylation
question
In glycolysis in the absence of oxygen, cells need a way to regenerate which compound?
answer
NAD+
question
Which of the following is the process in which glucose is oxidized to generate two molecules of pyruvate, and in which ATP and NADH are produced?
answer
None of the listed responses is correct.
question
Which of the following processes generates most of the NADH that delivers electrons to the electron transport chain?
answer
the citric acid cycle
question
Which of the following statements is the best explanation of what happens to the temperature and carbon dioxide concentration during a 1-hour class period in a classroom of 300 students if the heating and air conditioning is turned off and all doors are kept closed?
answer
Temperature and the level of carbon dioxide rise as heat and carbon dioxide are by-products of cellular respiration.
question
In eukaryotic cells, the components of the electron transport chain are located in or on __________.
answer
the inner membrane of the mitochondrion
question
Oxygen gas (O2) is one of the strongest oxidizing agents known. The explanation for this is that __________.
answer
the oxygen atom is very electronegative