7 Cellular Respiration and Fermentation

1. Cellular respiration can be most completely described as using energy released from breaking high-energy covalent bonds in organic molecules to make ATP. taking electrons from food and giving them to phosphate to make ATP. taking electrons from food and giving them to oxygen to make water and using the energy released to make ATP. converting higher-energy organic molecules to lower-energy organic molecules and using the energy released to make ATP. the production of pyruvate and carbon dioxide. Answer: C. Please see Concept 7.1. Oxygen is not the only chemical oxidizer, but it is the most important in living things for the extraction of energy. Discuss how oxygen extracts energy from wood in a campfire. © 2016 Pearson Education, Inc.

1. Cellular respiration can be most completely described as using energy released from breaking high-energy covalent bonds in organic molecules to make ATP. taking electrons from food and giving them to phosphate to make ATP. taking electrons from food and giving them to oxygen to make water and using the energy released to make ATP. converting higher-energy organic molecules to lower-energy organic molecules and using the energy released to make ATP. the production of pyruvate and carbon dioxide. Answer: C. Please see Concept 7.1. Oxygen is not the only chemical oxidizer, but it is the most important in living things for the extraction of energy. Discuss how oxygen extracts energy from wood in a campfire. © 2016 Pearson Education, Inc.

2. Which statement about glycolysis is true? It splits water. It uses oxygen. It occurs in the cytoplasm. It makes the most ATP compared to the two other steps. It makes lipids. Answer: C. See Concept 7.1. Glucose is split and partially oxidized to produce pyruvate molecules. Discuss whether glycolysis produces or uses ATP, and in what senses that can be answered. © 2016 Pearson Education, Inc. 4

2. Which statement about glycolysis is true? It splits water. It uses oxygen. It occurs in the cytoplasm. It makes the most ATP compared to the two other steps. It makes lipids. Answer: C. See Concept 7.1. Glucose is split and partially oxidized to produce pyruvate molecules. Discuss whether glycolysis produces or uses ATP, and in what senses that can be answered. © 2016 Pearson Education, Inc. 5

3. Which statement about the citric acid cycle is true? It occurs during the movement from the cytosol through the mitochondrial membranes. It makes ATP through substrate-level phosphorylation. It makes the most ATP compared to the two other steps. It occurs in the cytoplasm. It splits glucose. Answer: B. Contrast the citric acid cycle with glycolysis in terms of ATP production and oxygen use. © 2016 Pearson Education, Inc. 6

3. Which statement about the citric acid cycle is true? It occurs during the movement from the cytosol through the mitochondrial membranes. It makes ATP through substrate-level phosphorylation. It makes the most ATP compared to the two other steps. It occurs in the cytoplasm. It splits glucose. Answer: B. Contrast the citric acid cycle with glycolysis in terms of ATP production and oxygen use. © 2016 Pearson Education, Inc. 7

4. What do cells require to sustain high rates of glycolysis under anaerobic conditions? functioning mitochondria oxygen oxidative phosphorylation of ATP NAD+ All of the above are correct. Answer: D. See Concept 7.5. Anaerobic respiration depends on some other terminal oxidizer than oxygen. © 2016 Pearson Education, Inc. 8

4. What do cells require to sustain high rates of glycolysis under anaerobic conditions? functioning mitochondria oxygen oxidative phosphorylation of ATP NAD+ All of the above are correct. Answer: D. See Concept 7.5. Anaerobic respiration depends on some other terminal oxidizer than oxygen. © 2016 Pearson Education, Inc. 9

5. The energetic electron, taken from glucose or a breakdown product of glucose, is stripped of its energy to actively transport H+ into the intermembrane space. actively transport NAD+ into the intermembrane space. actively transport Na+ into the matrix. power facilitated diffusion of H+ into the matrix. actively transport H+ into the matrix. Answer: A. See Concept 7.4. The energy in glucose is converted into a proton gradient across the inner mitochondrial membrane. This is, in turn, converted into the chemical bond energy in ATP. © 2016 Pearson Education, Inc. 10

5. The energetic electron, taken from glucose or a breakdown product of glucose, is stripped of its energy to actively transport H+ into the intermembrane space. actively transport NAD+ into the intermembrane space. actively transport Na+ into the matrix. power facilitated diffusion of H+ into the matrix. actively transport H+ into the matrix. Answer: A. See Concept 7.4. The energy in glucose is converted into a proton gradient across the inner mitochondrial membrane. This is, in turn, converted into the chemical bond energy in ATP. © 2016 Pearson Education, Inc. 11

6. ATP synthase at the inner mitochondrial membrane makes ATP by which of the following methods? allowing Na+ to move down its electrochemical gradient allowing H+ to move against its electrochemical gradient facilitated diffusion of H+ active transport of H+ active transport of Na+ Answer: C. See Concept 7.4. Protons can move through the membrane via the stem-like part of the ATP synthase. © 2016 Pearson Education, Inc. 12

6. ATP synthase at the inner mitochondrial membrane makes ATP by which of the following methods? allowing Na+ to move down its electrochemical gradient allowing H+ to move against its electrochemical gradient facilitated diffusion of H+ active transport of H+ active transport of Na+ Answer: C. See Concept 7.4. Protons can move through the membrane via the stem-like part of the ATP synthase. © 2016 Pearson Education, Inc. 13

7. What is the purpose of fermentation reactions? to regenerate NAD+ so glycolysis can continue to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions to make additional ATP when respiration can’t make ATP fast enough to slow down cellular oxygen consumption when oxygen is scarce to make organic molecules that cells can store until oxygen becomes available Answer: A. Fermentation yields much less energy per molecule of glucose than respiration, but it allows for the continuation of energy extraction, which would otherwise stall. See Concept 7.5. © 2016 Pearson Education, Inc. 14

7. What is the purpose of fermentation reactions? to regenerate NAD+ so glycolysis can continue to make alcohol or lactic acid that cells can metabolize for energy under anaerobic conditions to make additional ATP when respiration can’t make ATP fast enough to slow down cellular oxygen consumption when oxygen is scarce to make organic molecules that cells can store until oxygen becomes available Answer: A. Fermentation yields much less energy per molecule of glucose than respiration, but it allows for the continuation of energy extraction, which would otherwise stall. See Concept 7.5. © 2016 Pearson Education, Inc. 15

8. During intense exercise, muscles lack sufficient oxygen, so what will the muscles use? alcoholic fermentation the citric acid cycle only glycolysis, with NAD not utilized lactic acid fermentation chemiosmosis Answer: D. Rather than alcoholic fermentation, muscles use lactic acid fermentation, which leads to the “burn” felt by muscles experiencing a buildup of lactic acid. See Concept 7.5. © 2016 Pearson Education, Inc. 16

8. During intense exercise, muscles lack sufficient oxygen, so what will the muscles use? alcoholic fermentation the citric acid cycle only glycolysis, with NAD not utilized lactic acid fermentation chemiosmosis Answer: D. Rather than alcoholic fermentation, muscles use lactic acid fermentation, which leads to the “burn” felt by muscles experiencing a buildup of lactic acid. See Concept 7.5. © 2016 Pearson Education, Inc. 17

9. If you were asked to examine a container in which you were told that glycolysis was being performed in a cell-free extract, you would test for the presence of lots of ADP. pyruvate. glucose. sucrose. acetate. Answer: B. See Concept 7.2. Glycolysis breaks glucose into two molecules of the organic acid pyruvate. Acetate is later produced before the start of the citric acid cycle. © 2016 Pearson Education, Inc. 18

9. If you were asked to examine a container in which you were told that glycolysis was being performed in a cell-free extract, you would test for the presence of lots of ADP. pyruvate. glucose. sucrose. acetate. © 2016 Pearson Education, Inc. 19

10. Which compound, if found in an aerobically respiring mitochondrion, would be the greatest surprise? ADP H+ FADH2 NADPH none of the above Answer: D. See Concept 7.3. NADPH is involved in photosynthesis, while NADH is found in cellular respiration. © 2016 Pearson Education, Inc. 20

10. Which compound, if found in an aerobically respiring mitochondrion, would be the greatest surprise? ADP H+ FADH2 NADPH none of the above © 2016 Pearson Education, Inc. 21

11. What can be broken down via cellular respiration? carbohydrate polymers fats amino acids monosaccharides All of the answers are correct. Answer: E. See Concept 7.6. A wide range of materials can be fed into cellular respiration. © 2016 Pearson Education, Inc. 22

11. What can be broken down via cellular respiration? carbohydrate polymers fats amino acids monosaccharides All of the answers are correct. © 2016 Pearson Education, Inc. 23

12. In the absence of oxygen, what process can a cell use to extract energy from food? anaerobic respiration alcoholic fermentation lactic acid fermentation B or C A–C Answer: E. See Concept 7.6. All three pathways named can operate without oxygen. Discuss which would provide the most energy from the same input molecule. © 2016 Pearson Education, Inc. 24

12. In the absence of oxygen, what process can a cell use to extract energy from food? anaerobic respiration alcoholic fermentation lactic acid fermentation B or C A–C © 2016 Pearson Education, Inc. 25

13. Which molecule does not have energy extracted from it, directly or indirectly, by electron transport? ATP NADH FADH2 pyruvate glucose Answer: A. See Concept 7.4. ATP is the product of electron transport and oxidative phosphorylation, while the other four choices are all, at some point, fed into the process leading to ATP synthesis. © 2016 Pearson Education, Inc. 26

13. Which molecule does not have energy extracted from it, directly or indirectly, by electron transport? ATP NADH FADH2 pyruvate glucose © 2016 Pearson Education, Inc. 27