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BIOL 1000 - Test 2 2014

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BIOL 1000
William Pietro

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. An inorganic phosphate (Pi) was added to GDP. B. The GDP was removed and GTP added. C. The GTP was hydrolyzed. D. 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. Dehydrogenases B. Isomerases C. Protein kinases D. 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. Add a chemical that deactivates the G-protein. B. Add a chemical that activates adenylyl cyclase. C. Add a chemical that increases the concentration of active phosphodiesterase. D. 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. Increased level of cyclic AMP B. Decreased level of active protein kinase A C. Increased number of adenylyl cyclase D. 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. A high proportion of unsaturated fatty acids in the plasma membrane. B. A high environmental temperature (e.g. 36°C) C. The increased addition of hydrogen atoms to phospholipid fatty acid chains. D. 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. Fatty acid chains B. Microfilaments C. Carbohydrate groups D. 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. Electrical gradient of the co-transported molecule. B. Extracellular concentration of the driving ion. C. Transfer rate of a terminal ATP phosphate to the symporter. D. 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. The removal of a ligand from the protein. B. Transfer of a terminal phosphate from ATP. C. Energy from a driving ion. D. A change in the protein’s three-dimensional shape. E. 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. The molecule composition includes many carbon atoms. B. The molecule composition lacks amino acids. C. The molecule composition does not include hydrogen bonding. D. 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. High solute concentration relative to that in the bag. B. Low solute concentration relative to that in the bag. C. Solute concentration equal to that in the bag. D. 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. When threonine concentration is low. B. When threonine concentration is high. C. When isoleucine concentration is high. D. 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. Exothermic, spontaneous reaction. B. Endothermic, spontaneous reaction. C. Exothermic, not a spontaneous reaction. D. 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 activat
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