Cellular Respiration 1. Enzymes are organic catalysts. How do they increase the rate of chemical reactions? a. By decreasing the free-energy change of the reaction b. By increasing the free-energy change of the reaction c. By raising the activation energy of the reaction d. By lowering the activation energy of the reaction 2. Catabolic and anabolic pathways are often coupled in a cell because a. The intermediates of a catabolic pathway are used in the anabolic pathway. b. Both pathways use the same enzymes. c. The free energy released from one pathway is used to drive the other pathway. d. Their enzymes are controlled by the same activators and inhibitors. 3. In the figure, which step of the citric acid cycle requires both NAD+ and ADP as reactants? a. Step 1 c. Step 3 b. Step 2 d. Step 4 1 4 2 3
4. One glucose molecule provides enough carbon atoms for two trips through the citric acid cycle. How many molecules of ATP are directly produced in two trips through the citric acid cycle? a. One c. Three b. Two d. Four 5. When a cell breaks down glucose, only about 40% of the energy is captured in ATP molecules. What happens to the remaining 60% of the energy? a. It is used to increase the order necessary for life to exist. b. It is lost as heat, in accordance with the second law of thermodynamics. c. It is stored as starch or glycogen for later use by the cell. d. It is released when the ATP molecules are hydrolyzed. 6. When substance A was added to an enzyme reaction, product formation decreased. The addition of more substrate did not increase product formation. From this we conclude that substance A could be a. Product molecules c. A competitive inhibitor b. An allosteric enzyme d. A noncompetitive inhibitor 7. Glycolysis is the first phase of aerobic cellular respiration. One of the enzymes at the beginning of glycolysis is PFK, phosphofructokinase, an allosteric enzyme. When ATP binds to the allosteric site on PFK, the enzyme changes shape and no longer functions. Which of the following statements best explains the importance of the enzyme PFK in glycolysis? a. PFK inhibits glycolysis when oxygen levels are high. b. PFK enables glycolysis to continue when no oxygen is present. c. PFK inhibits the production of ATP when ATP levels are high. d. PFK enhances the production of ATP when ATP levels are high. 8. Glycolysis releases free energy held in the bonds of glucose, and this energy is held in the these molecules: a. ATP, NADH, and CO2 b. ATP, NADH, and pyruvate c. ATP, NADPH, and RUBP d. ATP, CO2, and H2O
9. How many net ATP would be generated directly from glycolysis from the breakdown of 2 glucose molecules? a. 2 c. 8 b. 4 d. 12 10. Brown fat, which is found in newborn infants and hibernating mammals, has uncoupler proteins that, when activated, make the inner mitochondrial membrane leaky to H+. What is the function of brown fat? a. It produces more ATP than does regular fat and is also found in the flight muscles of geese and ducks, providing more energy for long-distance migrations. b. It lowers the ph of the intermembrane space, which results in the production of more ATP per gram than is produced by the oxidation of glucose or regular fat tissue. c. Because it dissipates the proton gradient, it generates heat through cellular respiration without producing ATP, thereby raising the body temperature of hibernating mammals or newborn infants. d. Its main function is insulation in endothermic animals where brown fat is common. 11. Which of the following provides evidence that glycolysis is one of the first metabolic pathways to have evolved? a. It relies on fermentation, which is characteristic of archaea and bacteria. b. It is found only in prokaryotes, whereas eukaryotes use mitochondria to produce ATP. c. It produces ATP only by oxidative phosphorylationi and does not involve redox reactions. d. It is nearly universal, occurs in the cytosol, and does not involve O2.
12. The release of the energy stored in glucose involves a series of reactions and processes. Which of the following correctly states the location and function of the named process? a. Citric acid cycle releases CO2 from organic intermediates and synthesizes ATP from ADP via substrate level phosphorylation. b. Glycolysis releases free energy from glucose to produce ATP by oxidative phosphorylation. c. Electron transport occurs in the cytoplasm and harvest the electrons from NADH and FADH2 to establish the proton gradient. d. Chemiosmosis occurs when an enzyme in the inner mitochondrial membrane produces carbon dioxide and water from NADH and ATP. 13. Oxidative phosphorylation is said to couple two reactions together. Which two reactions does it bring together? a. The endergonic flow of electrons through the ETC with the exergonic movement of protons across the cristae membrane to create a proton gradient b. The exergonic flow of electrons through the ETC with the endergonic pumping of protons across the cristae membrane to create a proton gradient c. The flow of protons from glycolysis to the citric acid cycle d. The production of ATP from the anaerobic phase with the aerobic phase 14. Rotenone acts as a common and potent poison that works by inhibiting complex I of the electron transport chain. In cells treated with rotenone, NADH is no longer capable of accepting and passing along electrons from complex I to ubiquinone. A researcher treats a group of cells with rotenone and measures oxygen consumption over time. Oxygen consumption decreases, but does not cease. How would you explain this result? a. The concentration of rotenone is not high enough; the inhibition is not effective. b. FADH2 donates electrons to complex II, bypassing the inhibited complex I. c. Oxygen is consumed elsewhere in the cells. d. Oxygen is consumed by complex IV, which is not inhibited in this case.
Questions 15-17 refer to the following diagram, which represents the breakdown of the carbon chain of glucose during cellular respiration. 15. Which of the following is represented by the process labeled I? a. Aerobic respiration in the mitochondria b. The splitting of glucose into two ATP and two pyruvate molecules c. The conversion of glucose into two lactate molecules by fermentation d. A series of enzyme-mediated reactions that occur in the cytosol 16. Which of the following is not required by process II? a. Transport of a metabolic intermediated into the mitochondria b. The direct participation of oxygen c. The transfer of hydrogen atoms from one of the carbons to a coenzyme d. Enzymes 17. Which of the following is the identity of molecule D? a. Carbon dioxide c. Pyruvate b. Glucose d. ATP
18. Which of the following is not true regarding the processes represented above? a. Reaction A can do biological work. b. The reaction profile of ATP synthesis is more similar to reaction A than B. c. Reactions A and B have the same free energy change, just in opposite directions. d. The activation energy of reaction A is greater than the activation energy of reaction B. 19. Glycolysis does not require oxygen to occur in cells. However, under anaerobic conditions, glycolysis normally requires fermentation pathways to occur to continue to produce ATP. Which best describes why glycolysis is dependent on fermentation under anaerobic conditions? a. Glycolysis requires fermentation to produce more glucose as a substrate. b. Glycolysis requires fermentation to synthesize lactic acid that is used as an enzyme cofactor of hexokinase (which catalyzes the first step of glycolysis). c. Glycolysis requires fermentation to generate ATP molecules to complete early steps of the pathway. d. Glycolysis requires fermentation to generate pyruvate for a later step in the process.
Questions 20-21 A respirometer is a container used to measure the amount of oxygen consumed by an organism. A respirometer was used to determine how environmental temperature affects the uptake of oxygen in one 300-gram rate and one 50-gram mouse. The results of this experiment are shown on the graph. 20. Which of the following statements best explains why oxygen is taken up more rapidly at 12 o C than at 20 o C? a. Oxygen is more soluble in blood at lower temperatures. b. At 12 o C a higher rate of oxygen consumption is required to maintain a high body temperature. c. In colder temperature, more heat is lost at the surface of the skin and the heat is replaced by deeper breathing. d. Oxygen is taken up more rapidly because of the greater expansion of the lungs caused by the loss of heat. 21. Which of the following hypotheses is best supported by the results of this experiment? a. Metabolic rate per gram of tissue is higher in smaller mammals. b. Mice produce less CO2 per gram of tissue than do rats. c. Rats consume more food per gram of tissue than do mice. d. Rats lose more heat per gram of tissue than do mice.
Questions 22-23 refer to the following graphs. 22. Calculate the free energy change ( G) of the process represented in graph B. 23. Calculate the activation energy (EA) of the process represented in graph A. Questions 24-26 refer to the following table Location Substrate Product NADH FADH2 ATP Cytosol Glucose 2 pyruvate 2 0 2 Mitochondria Pyruvate Acetyl-CoA & CO2 1 0 0 Mitochondria Acetyl-CoA 2 CO2 3 1 1 Mitochondria Palmitoyl- CoA 8 Acetyl-CoA 7 7 0 24. According to the table, how many NADH are produced from the complete oxidation of 1 molecule of palmitoyl-coa to 16 carbon dioxide molecules? 25. How many acetyl-coa molecules can be produced from 1 glucose molecule? 26. How many pyruvate molecules need to be completely oxidized to carbon dioxide to produce 24 NADH molecules?
1. D 2. C 3. C 4. B 5. B 6. D 7. C 8. B 9. B 10. C 11. D 12. A 13. B 14. B 15. B 16. B 17. A 18. A 19. C 20. B 21. A 22. -6 kj 23. 10 kj 24. 31 25. 2 26. 6
Photosynthesis 1. Groups of photosynthetic pigment molecules organized in the thylakoid membranes are called a. Photosystems c. Chlorophyll. b. Carotenoids. d. Grana. 2. The main products of the light dependent reactions of photosynthesis are a. NADPH and FADH2. b. NADPH and ATP. 3. The major product of the Calvin cycle is a. Rubisco b. Ribulose bisphosphate c. ATP and FADH2. d. ATP and CO2. c. Pyruvate d. Glyceraldehyde-3-phosphate 4. Which of the following is mismatched with its location? a. Photosystems thylakoid membrane b. Electron transport chain thylakoid membrane c. Calvin cycle stroma d. ATP Synthesis double membrane surrounding chloroplast 5. Photorespiration occurs when the levels of CO2 are relatively low. And the enzyme rubisco catalyzes its release from the plant, rather than fixing it into an organic acid. CAM plants avoid photorespiration by a. Fixing CO2 into organic acids during the night; these acids then release CO2 during the day b. Performing the Calvin cycle at night c. Fixing CO2 into four-carbon compounds in the mesophyll, which immediately release CO2 in the bundle-sheath cells d. Keeping their stomata open during the day 6. When light energy boosts electrons from the chlorophyll known as P680 to the primary electron acceptor, P680 has its electron holes filled by electrons from a. Photosystem I b. Photosystem II c. Water d. CO2 Questions 7-8: You are conducting an experiment to determine the effect of different wavelengths on the absorption of carbon dioxide as an indicator of the rate of photosynthesis in aquatic ecosystems. If the rate of photosynthesis increases, the amount of carbon dioxide in the environment will decrease and vice versa. You ve added an indicator to each solution. When the carbon dioxide concentration decreases, the color of the indicator solution also changes.
Small aquatic plants are placed into three containers of water mixed with carbon dioxide and indicator solution. Container A is placed under normal sunlight, B under green light, and C under red light. The containers are observed for a 24-hour period. 7. Based on your knowledge of the process of photosynthesis, the plant in the container placed under red light would probably a. Absorb no CO2. b. Absorb the same amount of CO2 as the plants under both the green light and normal sunlight. c. Absorb less CO2 than the plants under green light. d. Absorb more CO2 than the plants under green light. 8. Carbon dioxide absorption is an appropriate indicator of photosynthesis because a. CO2 is needed to produce sugars in the Calvin cycle. b. CO2 is needed to complete the light reactions. c. Plants produce oxygen gas by splitting CO2. d. The energy in CO2 is used to produce ATP and NADPH. 9. The process in photosynthesis that bears the most resemblance to chemiosmosis and oxidative phosphorylation in cell respiration is called a. Glycolysis b. Linear electron flow c. ATP synthase coupling d. Substrate level phosphorylation 10. Plants give off oxygen as a waste product of photosynthesis. This oxygen comes from a. The Krebs cycle b. The Calvin cycle c. Photolysis d. Photorespiration 11. Which of the following statements is correct about cyclic photophosphorylation? a. ATP is produced by light energy. b. This process occurs when a chloroplast runs low on ATP. c. Both NADPH and ATP are involved in this process. d. Only P680 is directly involved, not P700. 12. How many turns of the Calvin cycle are required to produce one molecule of glucose? a. 1 b. 2 c. 3 d. 6 13. Which of the following is NOT directly associated with photosytem II? a. Harvesting light energy by chlorophyll b. Release of oxygen c. Splitting of water d. Production of NADPH
Questions 13-19 Indicate which of the following events occurs during a. Light-dependent reactions b. Light-independent reactions c. Both sets of reactions d. Neither set of reactions 14. Oxygen is released. 15. Carbond gets reduced. 16. Oxidative photophosphorylation 17. CO2 is released 18. Electrons flow through an electron transport chain. 19. Oxidation of NADPH 20. Reduction of NADP+ 21. Where in the cell is ATP-synthase located? a. In the nuclear membrane b. In the thylakoid membrane of the chloroplast c. In the cristae membrane of the mitochondria d. Both b and c 22. Which of the following is NOT required for photosynthesis to occur? a. CO2 b. O2 c. ATP d. NADP+
1. A 2. B 3. D 4. D 5. A 6. C 7. D 8. A 9. B 10. C 11. A 12. D 13. A 14. B 15. A 16. D 17. A 18. B 19. A 20. D 21. D 22. B