Page 1 of 7 BIOL 1000 Section M â Test 2 â March 7, 2014 Note: Questio
Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
BIOL 1000 Section M – Test 2 – March 7, 2014 Note: Question and Answer Order Varied with Test Version 1. VERSION Question 2. An activated G-protein, associated with the cyclic AMP pathway, returns to an inactivated state. What has caused this G-protein inactivation? A. B. C. D.
An inorganic phosphate (Pi) was added to GDP. The GDP was removed and GTP added. The GTP was hydrolyzed. The two terminal GTP phosphates were removed.
3. Phosphorylation cascades, associated with some signal transduction pathways, are directly associated with which of the following? A. B. C. D.
Dehydrogenases Isomerases Protein kinases Hydrolases
4. The enzyme, glycogen phosphorylase, catalyzes the conversion of glycogen to glucose-6-phosphate. This enzyme is activated by active protein kinase A and thus is associated with the cyclic AMP pathway. Based on your knowledge of the cyclic AMP pathway indicate a method by which a researcher could experimentally activate glycogen phosphorylase. A. B. C. D.
Add a chemical that deactivates the G-protein. Add a chemical that activates adenylyl cyclase. Add a chemical that increases the concentration of active phosphodiesterase. Add a chemical that increases the conversion of cyclic AMP to AMP.
5. A researcher experimentally inhibits phosphodiesterase (PDE). Which of the following would you expect to find in this situation? A. B. C. D.
Increased level of cyclic AMP Decreased level of active protein kinase A Increased number of adenylyl cyclase Decreased activation of G-protein coupled receptors
6. A cell contains a high concentration of active desaturase. Which would you expect to find associated with this situation? A. B. C. D.
A high proportion of unsaturated fatty acids in the plasma membrane. A high environmental temperature (e.g. 36°C) The increased addition of hydrogen atoms to phospholipid fatty acid chains. An increased proportion of fatty acid chains not containing carbon-carbon double bonds.
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
7. Which of the following would you expect to find associated with the extracellular portion of a transmembrane protein? A. B. C. D.
Fatty acid chains Microfilaments Carbohydrate groups Cholesterol
8. Glucose is moved into intestinal cells using a Na+/Glucose symporter. Which of the following would impact the rate of glucose transport across the membrane of an intestinal cell? A. B. C. D.
Electrical gradient of the co-transported molecule. Extracellular concentration of the driving ion. Transfer rate of a terminal ATP phosphate to the symporter. Movement of the driving ion against its concentration gradient.
9. Na+ passively diffuses into a cell through an open channel. Which of the following situations will result in the fastest rate of diffusion? Note: the same high extracellular Na+ concentration and low cytosolic Na+ concentration applies to each scenario. A. The charge inside the cell relative to outside the cell (membrane potential) is -70mv. B. The charge inside the cell relative to outside the cell (membrane potential) is +20mv. C. The charge inside the cell relative to outside the cell (membrane potential) is 0mv. 10. The opening of a gated channel involves A. B. C. D. E.
The removal of a ligand from the protein. Transfer of a terminal phosphate from ATP. Energy from a driving ion. A change in the protein’s three-dimensional shape. All of the above.
11. A researcher discovers a new molecule in a cell and determines that it is NOT a protein. This decision was likely based on the fact that A. B. C. D.
The molecule composition includes many carbon atoms. The molecule composition lacks amino acids. The molecule composition does not include hydrogen bonding. The molecule contains covalent bonds.
12. A bag, permeable to only water, contains an unknown solute concentration. When placed into a beaker containing an unknown solution, it shrinks. What is the likely composition of the unknown solution in the beaker relative to that in the bag? A. B. C. D.
High solute concentration relative to that in the bag. Low solute concentration relative to that in the bag. Solute concentration equal to that in the bag. Unable to determine based on the provided information. Page 2 of 7
Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
13. Threonine is converted to isoleucine through a series of enzyme-catalyzed steps. The first reaction in this series requires the allosteric enzyme threonine deaminase. Through feedback inhibition, isoleucine regulates its own synthesis by binding to and inhibiting threonine deaminase. Under which of the following conditions would you expect to see an increased proportion of the threonine deaminase in a high affinity state (readily binds the threonine substrate)? A. B. C. D.
When threonine concentration is low. When threonine concentration is high. When isoleucine concentration is high. When isoleucine concentration is low.
14. The products of a chemical reaction have less potential energy than the reactants. Which of the following best describes this reaction? A. B. C. D.
Exothermic, spontaneous reaction. Endothermic, spontaneous reaction. Exothermic, not a spontaneous reaction. Endothermic, not a spontaneous reaction.
15. The overall process of aerobic cellular respiration consists of many individual reactions some of which have a negative △G and others that have a positive △G. Why is cellular respiration overall considered a catabolic pathway? A. Adding together the change in free energy associated with each individual reaction results in an overall negative change in free energy. B. The activation energy of each individual reaction is less than if cellular respiration occurred as only one reaction. C. Adding together the activation energy associated with each reaction results in an overall negative change in activation energy. D. The sum total of all the △Gs associated with the cellular respiration reactions is positive. 16. Which of the following is true of enzymes A. B. C. D.
They are always in an active or high-affinity state. They are a non-protein class of molecules. They maintain the activation energy of a reaction. They do not alter the free energy of a reaction.
17. An animal has a normal body temperature of 25°C. A system within this animal contains 0.005mM of substrate and 0.002mM of the associated enzyme. The enzyme works best at pH 5. Which of the following would increase the rate of this enzymecatalyzed reaction? A. B. C. D.
Increasing the pH to pH 2. Increasing the enzyme concentration. Decreasing the substrate concentration. Decreasing the temperature to 15°C
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
18. The following pathway description applies to this question and the following question. During a laboratory experiment, you discover a metabolic pathway composed of three coupled enzyme-catalyzed reactions (A, B and C). Reaction A has a △G of -20 kcal/mol, Reaction B has a △G of +10 kcal/mol Reaction C has a △G of -10 kcal/mol What can you say about this pathway? A. B. C. D.
It is catabolic. It is anabolic. It can be classified as both endergonic and anabolic. It can be classified as both endergonic and catabolic.
19. Use the metabolic pathway described in the question above for this question. If you reduce the amount of the enzyme associated with each of the reactions (A, B and C) in half, what will be the overall △G for this pathway? A. B. C. D.
-10 kcal/mol -15 kcal/mol -20 kcal/mol -40 kcal/mol
20. What will occur during this hypothetical situation? NAD+ is no longer found in the matrix of a mitochondrion in a plant cell. A. B. C. D. E.
FADH2 will not be synthesized but NADH will be. NADPH will not be synthesized. Acetyl-CoA will be synthesized but not oxaloacetate. Citrate will not be synthesized. None of the above.
21. A mitochondrion has a high number of uncoupling proteins in the inner membrane. What would you expect to find in comparison to a mitochondrion lacking these uncoupling proteins? A. Weaker proton-motive force. B. No change in the rate of electron transfer through the electron transport chain. C. No change in the energy released during electron transfers through the electron transport chain. D. All of the above. 22. What is the purpose of ethanol fermentation in yeast? A. B. C. D.
To reduce NAD+ To oxidize NADH To convert pyruvate into Acetyl CoA To synthesize one ATP per glucose via substrate level phosphorylation.
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
23. How many “turns” of the Citric Acid Cycle (Kreb Cycle) occur per glucose molecule? A. B. C. D.
0 1 2 4
24. Which of the following statements applies to the reaction below?
A. B. C. D.
FAD loses electrons. FADH2 is oxidized. Succinate is oxidized Succinate is reduced.
25. What is the maximum number of Acetyl CoA produced, under anaerobic conditions, from 10 glucose molecules that each undergo complete glycolysis? A. 0 B. 10 C. 20 D. 30 26. Which of the following would NOT impact the rate of aerobic cellular respiration? A. B. C. D.
Increasing the availability of CO2 Reducing the availability of FAD. Increasing the concentration of ATP. Reducing the availability of O2.
27. Which of the following is common to BOTH plant and animal cells? A. B. C. D. E.
NADPH Rubisco Pyruvate Malate None of the above
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
28. Based on the data presented in the figure below, which wavelength of light is best absorbed by chlorophyll a?
A. B. C. D.
450 nm 500 nm 650 nm 700 nm
29. Which of the following is/are required for converting CO2 into an organic molecule in photoautotrophs. A. B. C. D.
Rubisco Water High energy electrons All of the above
30. Which of the following is directly associated with a carotenoid photosynthetic pigment? A. B. C. D.
Non-polar amino acids Conjugated system Polar-charged amino acids NADPH
31. Why is cyclic electron transport, in photosynthesis, necessary? A. B. C. D.
It helps increase the amount of NADPH available for the Calvin Cycle. It is involved in pumping additional protons to the stroma. It is involved in strengthening the proton motive force. It donates an electron and thus energy back to Photosystem II.
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
32. Why are two photosystems necessary for the production of NADPH? A. Proton pumps associated with the electron transport chains of both Photosystem I and II are required to create the strong concentration gradient needed for NADPH production. B. The light energy absorbed by Photosystem II alone is not enough to transport an electron through to NADP+. C. Only electrons associated with different wavelengths of light (700nm and 680nm) are accepted by NADP+. D. Photons absorbed by Photosystem I provide energy for the hydrolysis of water and thus indirectly provide energy for the donation of an electron to Photosystem II. 33. CAM plants keep their stomata closed in the daytime, preventing the entry of CO2 into the plant cells, yet are still able to photosynthesize all day. How is this possible? A. B. C. D.
They fix CO2 into organic molecules during the night. CO2 diffuses through the cell wall during the day. The stomata are not associated with photosynthesis. NADPH is stored during the night and used during the day.
END OF TEST.
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BIOL 1000 Section M – Test 2 – March 7, 2014 Note: Question and Answer Order Varied with Test Version 1. VERSION Question 2. An activated G-protein, associated with the cyclic AMP pathway, returns to an inactivated state. What has caused this G-protein inactivation? A. B. C. D.
An inorganic phosphate (Pi) was added to GDP. The GDP was removed and GTP added. The GTP was hydrolyzed. The two terminal GTP phosphates were removed.
3. Phosphorylation cascades, associated with some signal transduction pathways, are directly associated with which of the following? A. B. C. D.
Dehydrogenases Isomerases Protein kinases Hydrolases
4. The enzyme, glycogen phosphorylase, catalyzes the conversion of glycogen to glucose-6-phosphate. This enzyme is activated by active protein kinase A and thus is associated with the cyclic AMP pathway. Based on your knowledge of the cyclic AMP pathway indicate a method by which a researcher could experimentally activate glycogen phosphorylase. A. B. C. D.
Add a chemical that deactivates the G-protein. Add a chemical that activates adenylyl cyclase. Add a chemical that increases the concentration of active phosphodiesterase. Add a chemical that increases the conversion of cyclic AMP to AMP.
5. A researcher experimentally inhibits phosphodiesterase (PDE). Which of the following would you expect to find in this situation? A. B. C. D.
Increased level of cyclic AMP Decreased level of active protein kinase A Increased number of adenylyl cyclase Decreased activation of G-protein coupled receptors
6. A cell contains a high concentration of active desaturase. Which would you expect to find associated with this situation? A. B. C. D.
A high proportion of unsaturated fatty acids in the plasma membrane. A high environmental temperature (e.g. 36°C) The increased addition of hydrogen atoms to phospholipid fatty acid chains. An increased proportion of fatty acid chains not containing carbon-carbon double bonds.
Page 1 of 7
Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
7. Which of the following would you expect to find associated with the extracellular portion of a transmembrane protein? A. B. C. D.
Fatty acid chains Microfilaments Carbohydrate groups Cholesterol
8. Glucose is moved into intestinal cells using a Na+/Glucose symporter. Which of the following would impact the rate of glucose transport across the membrane of an intestinal cell? A. B. C. D.
Electrical gradient of the co-transported molecule. Extracellular concentration of the driving ion. Transfer rate of a terminal ATP phosphate to the symporter. Movement of the driving ion against its concentration gradient.
9. Na+ passively diffuses into a cell through an open channel. Which of the following situations will result in the fastest rate of diffusion? Note: the same high extracellular Na+ concentration and low cytosolic Na+ concentration applies to each scenario. A. The charge inside the cell relative to outside the cell (membrane potential) is -70mv. B. The charge inside the cell relative to outside the cell (membrane potential) is +20mv. C. The charge inside the cell relative to outside the cell (membrane potential) is 0mv. 10. The opening of a gated channel involves A. B. C. D. E.
The removal of a ligand from the protein. Transfer of a terminal phosphate from ATP. Energy from a driving ion. A change in the protein’s three-dimensional shape. All of the above.
11. A researcher discovers a new molecule in a cell and determines that it is NOT a protein. This decision was likely based on the fact that A. B. C. D.
The molecule composition includes many carbon atoms. The molecule composition lacks amino acids. The molecule composition does not include hydrogen bonding. The molecule contains covalent bonds.
12. A bag, permeable to only water, contains an unknown solute concentration. When placed into a beaker containing an unknown solution, it shrinks. What is the likely composition of the unknown solution in the beaker relative to that in the bag? A. B. C. D.
High solute concentration relative to that in the bag. Low solute concentration relative to that in the bag. Solute concentration equal to that in the bag. Unable to determine based on the provided information. Page 2 of 7
Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
13. Threonine is converted to isoleucine through a series of enzyme-catalyzed steps. The first reaction in this series requires the allosteric enzyme threonine deaminase. Through feedback inhibition, isoleucine regulates its own synthesis by binding to and inhibiting threonine deaminase. Under which of the following conditions would you expect to see an increased proportion of the threonine deaminase in a high affinity state (readily binds the threonine substrate)? A. B. C. D.
When threonine concentration is low. When threonine concentration is high. When isoleucine concentration is high. When isoleucine concentration is low.
14. The products of a chemical reaction have less potential energy than the reactants. Which of the following best describes this reaction? A. B. C. D.
Exothermic, spontaneous reaction. Endothermic, spontaneous reaction. Exothermic, not a spontaneous reaction. Endothermic, not a spontaneous reaction.
15. The overall process of aerobic cellular respiration consists of many individual reactions some of which have a negative △G and others that have a positive △G. Why is cellular respiration overall considered a catabolic pathway? A. Adding together the change in free energy associated with each individual reaction results in an overall negative change in free energy. B. The activation energy of each individual reaction is less than if cellular respiration occurred as only one reaction. C. Adding together the activation energy associated with each reaction results in an overall negative change in activation energy. D. The sum total of all the △Gs associated with the cellular respiration reactions is positive. 16. Which of the following is true of enzymes A. B. C. D.
They are always in an active or high-affinity state. They are a non-protein class of molecules. They maintain the activation energy of a reaction. They do not alter the free energy of a reaction.
17. An animal has a normal body temperature of 25°C. A system within this animal contains 0.005mM of substrate and 0.002mM of the associated enzyme. The enzyme works best at pH 5. Which of the following would increase the rate of this enzymecatalyzed reaction? A. B. C. D.
Increasing the pH to pH 2. Increasing the enzyme concentration. Decreasing the substrate concentration. Decreasing the temperature to 15°C
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
18. The following pathway description applies to this question and the following question. During a laboratory experiment, you discover a metabolic pathway composed of three coupled enzyme-catalyzed reactions (A, B and C). Reaction A has a △G of -20 kcal/mol, Reaction B has a △G of +10 kcal/mol Reaction C has a △G of -10 kcal/mol What can you say about this pathway? A. B. C. D.
It is catabolic. It is anabolic. It can be classified as both endergonic and anabolic. It can be classified as both endergonic and catabolic.
19. Use the metabolic pathway described in the question above for this question. If you reduce the amount of the enzyme associated with each of the reactions (A, B and C) in half, what will be the overall △G for this pathway? A. B. C. D.
-10 kcal/mol -15 kcal/mol -20 kcal/mol -40 kcal/mol
20. What will occur during this hypothetical situation? NAD+ is no longer found in the matrix of a mitochondrion in a plant cell. A. B. C. D. E.
FADH2 will not be synthesized but NADH will be. NADPH will not be synthesized. Acetyl-CoA will be synthesized but not oxaloacetate. Citrate will not be synthesized. None of the above.
21. A mitochondrion has a high number of uncoupling proteins in the inner membrane. What would you expect to find in comparison to a mitochondrion lacking these uncoupling proteins? A. Weaker proton-motive force. B. No change in the rate of electron transfer through the electron transport chain. C. No change in the energy released during electron transfers through the electron transport chain. D. All of the above. 22. What is the purpose of ethanol fermentation in yeast? A. B. C. D.
To reduce NAD+ To oxidize NADH To convert pyruvate into Acetyl CoA To synthesize one ATP per glucose via substrate level phosphorylation.
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
23. How many “turns” of the Citric Acid Cycle (Kreb Cycle) occur per glucose molecule? A. B. C. D.
0 1 2 4
24. Which of the following statements applies to the reaction below?
A. B. C. D.
FAD loses electrons. FADH2 is oxidized. Succinate is oxidized Succinate is reduced.
25. What is the maximum number of Acetyl CoA produced, under anaerobic conditions, from 10 glucose molecules that each undergo complete glycolysis? A. 0 B. 10 C. 20 D. 30 26. Which of the following would NOT impact the rate of aerobic cellular respiration? A. B. C. D.
Increasing the availability of CO2 Reducing the availability of FAD. Increasing the concentration of ATP. Reducing the availability of O2.
27. Which of the following is common to BOTH plant and animal cells? A. B. C. D. E.
NADPH Rubisco Pyruvate Malate None of the above
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
28. Based on the data presented in the figure below, which wavelength of light is best absorbed by chlorophyll a?
A. B. C. D.
450 nm 500 nm 650 nm 700 nm
29. Which of the following is/are required for converting CO2 into an organic molecule in photoautotrophs. A. B. C. D.
Rubisco Water High energy electrons All of the above
30. Which of the following is directly associated with a carotenoid photosynthetic pigment? A. B. C. D.
Non-polar amino acids Conjugated system Polar-charged amino acids NADPH
31. Why is cyclic electron transport, in photosynthesis, necessary? A. B. C. D.
It helps increase the amount of NADPH available for the Calvin Cycle. It is involved in pumping additional protons to the stroma. It is involved in strengthening the proton motive force. It donates an electron and thus energy back to Photosystem II.
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Test 2 – Section M – March 7 – FOR POSTING ON MOODLE
32. Why are two photosystems necessary for the production of NADPH? A. Proton pumps associated with the electron transport chains of both Photosystem I and II are required to create the strong concentration gradient needed for NADPH production. B. The light energy absorbed by Photosystem II alone is not enough to transport an electron through to NADP+. C. Only electrons associated with different wavelengths of light (700nm and 680nm) are accepted by NADP+. D. Photons absorbed by Photosystem I provide energy for the hydrolysis of water and thus indirectly provide energy for the donation of an electron to Photosystem II. 33. CAM plants keep their stomata closed in the daytime, preventing the entry of CO2 into the plant cells, yet are still able to photosynthesize all day. How is this possible? A. B. C. D.
They fix CO2 into organic molecules during the night. CO2 diffuses through the cell wall during the day. The stomata are not associated with photosynthesis. NADPH is stored during the night and used during the day.
END OF TEST.
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