Cellular Respiration and Fermentation

1. Chapter 9 Cellular Respiration and Fermentation Questions prepared by Jung Choi Georgia Institute of Technology

2. Cellular respiration can best be 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

3. During glycolysis, for each mole of glucose oxidized to pyruvate • 6 moles of ATP are produced. • 4 moles of ATP are used, and 2 moles of ATP are produced. • 2 moles of ATP are used, and 4 moles of ATP are produced. • 2 moles of ATP are used, and 2 moles of ATP are produced. • net 4 moles of ATP are produced.

4. GlycolysisTo sustain high rates of glycolysis under anaerobic conditions, cells require • functioning mitochondria. • oxygen. • oxidative phosphorylation of ATP. • NAD+. • All of the above are correct.

5. What pathways generate reduced electron carriers? • The citric acid cycle • Glycolysis • Pyruvate oxidation • All of the above • Glycolysis and the citric acid cycle only

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

7. Electron Transport Chain and Respiration 1Rotenone inhibits complex I (NADH dehydrogenase). When complex I is completely inhibited, cells will • neither consume oxygen nor make ATP. • not consume oxygen and will make ATP only through glycolysis and fermentation. • not consume oxygen and will make ATP only through substrate-level phosphorylation. • consume less oxygen but still make some ATP through both glycolysis and respiration.

8. Electron Transport Chain and Respiration 2This graph shows the oxygen concentration in a sealed chamber containing isolated mitochondria plus citrate. The addition of ADP • stimulates respiration by acting as a substrate for the F1 ATPase. • stimulates respiration by speeding up glycolysis. • inhibits respiration by depleting oxygen.

9. Electron Transport Chain and Respiration 3Rotenone inhibits complex I of the electron transport chain and thereby inhibits respiration. What compound X might restore respiration in the presence of rotenone? Hint: Examine the citric acid cycle. • NADH • isocitrate • succinate • malate • pyruvate

10. Energy and RespirationNewborn mammals have a specialized organ called brown fat, where cells burn fat to CO2 without capturing the energy to reduce electron carriers or make ATP. This energy may be used, instead, to • synthesize glucose from CO2. • directly power muscle contraction. • provide energy for endergonic biosynthetic reactions. • generate heat.

11. Evolution of Metabolic PathwaysGlycolysis is found in all domains of life and is therefore believed to be ancient in origin. What can be said about the origin of the citric acid cycle, the electron transport chain, and the F1 ATPase? • They evolved after photosynthesis generated free oxygen. • They evolved before photosynthesis and used electron acceptors other than oxygen. • Individual enzymes were present before photosynthesis but served other functions, such as amino acid metabolism. • They evolved when the ancestral eukaryotes acquired mitochondria.

12. The purpose of fermentation reactions is • 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

13. If your muscle cells used alcoholfermentation instead of lactic acid fermentation, which of the following might occur? • Your cells would make more ATP in anaerobic conditions. • Your cells would not be able to produce ATP in anaerobic conditions. • You might become drunk when sprinting to catch a bus. • Your cells would recycle less NADH to NAD+ in anaerobic conditions. • Your cells would release less CO2 in anaerobic conditions.

14. Mitochondria and Alternative Energy SourcesPetite mutants of yeast have defective mitochondria incapable of oxidative phosphorylation. What carbon sources can these mutants use to grow? • glucose • fatty acids • pyruvate • all of the above • none of the above

15. Catabolism and AnaerobiosisDuring intense exercise, as muscles go into anaerobiosis, the body will increase its consumption of • fats. • proteins. • carbohydrates. • all of the above

16. Regulation of MetabolismHow will a respiratory uncoupler affect the rates of glycolysis and the citric acid cycle? • Both will increase. • Both will decrease. • Only glycolysis will increase because of fermentation. • Only the citric acid cycle will increase.

17. What is the probable effect on ATP productionof a low-calorie diet? • ATP production would decrease due to a reduction in the availability of fuel molecules. • ATP production would increase as stored fats are catabolized. • ATP production would increase if most calories were provided by fats and decrease if most calories were provided by high-fiber grains. • ATP production would remain constant as stored fats or other body molecules are oxidized. • ATP production would remain constant as long as the exercise level was increased.