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Chapter 8-10 Review Homework Questions |
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1. You set up a series of experiments to
monitor the rates of a reaction. The reaction is enzyme mediated. In the reaction A → B + C. For each
experiment in this series, you continuously add the reactant
A and monitor its concentration, so that the amount of A remains constant
over time. For each group of
experiments, explain how the differences in experimental conditions could
affect the reaction. a.
You compare two simultaneous experiments. In experiment 1, you use X amount
of the enzyme. In experiment 2, you use 2X amount of the same enzyme. b.
You compare two simultaneous experiments. In both, you use equal amounts of
the enzyme. In one, you allow the products to accumulate over time. In the
other, you remove the products as they are produced. c. You run two experiments and use equal amounts of the enzyme in both. One is run at 15⁰ C and one is run at 35⁰ C. The enzyme that you are using is isolated from human stomach juices. |
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2. How do competitive and noncompetitive inhibition of an enzyme differ? Explain how allosteric regulation of an enzyme occurs. |
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3. Explain how feedback mechanisms may be use to regulate enzyme-mediated metabolic pathways. |
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4. What reactions do photosynthesis and glycolysis have in common? |
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5. If the Krebs cycle does not require oxygen, why does cellular respiration stop after glycolysis when no oxygen is present? |
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6. Many organisms can withstand periods
of oxygen debt (anaerobic conditions). Yeast undergoing oxygen debt convert pyruvic acid to ethanol and carbon dioxide. Animals
undergoing oxygen debt convert pyruvic acid to
lactic acid. Pyruvic acid is fairly non-toxic. Both
ethanol and lactic acid are quite toxic even in small amounts. Explain why this conversion has to occur in organisms even though it may kill them. |
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7. The metabolic pathways of organisms living today evolved over a long period of time--undoubtedly in stepwise fashion because of their complexity. Put the following processes in the order in which they might have most likely evolved and give a short explanation for your arrangement: Krebs Cycle, Electron Transport, Glycolysis, Photosynthesis. |
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8. All living organisms require a constant supply of ATP to maintain life. If no light is available, how can a plant make ATP? |
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9. What makes
C4 photosynthesis more efficient than C3 photosynthesis in tropical climates? How is |
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10. Photosynthesis most likely evolved very
early in Earth's history. Central to the evolution of photosynthesis was the
evolution of the enzyme rubisco (an abbreviation
for ribulose biosphosphate
carboxylase oxidase). To
the best of our knowledge, all photosynthetic plants use rubisco.
Rubisco's funciton is to
supply carbon dioxide to the Calvin cycle; however it only does this if the
ratio of carbon dioxide to oxygen is relatively high (FYI- a "relatively
high" ratio of carbon dioxide to oxygen is 0.03% carbon dioxide to 20%
oxygen). When the carbon dioxide-to-oxygen ratio becomes low, the role of rubisco switches and it catalyzes photorespiration, the
breakdown of glucose to carbon dioxide and water. a.
Why do we view photorespiration as a "mistake" in the functioning
of a cell? b. Rubisco is thought to have evolved when the earth's
atmosphere was reducing (had very little oxygen
in it). How does this help to explain Rubisco's
quirk? |
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