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18.E: Microbial Metabolism (Exercises)

 

These are homework exercises to accompany Kaiser's "Microbiology" TextMap. Microbiology is the study of microorganisms, which are defined as any microscopic organism that comprises either a single cell (unicellular), cell clusters or no cell at all (acellular). This includes eukaryotes, such as fungi and protists, and prokaryotes. Viruses and prions, though not strictly classed as living organisms, are also studied.

18.3: Aerobic Respiration

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  1. Briefly describe aerobic respiration. (ans)
  2. Give the overall chemical reaction for aerobic respiration. (ans)
  3. During aerobic respiration, glucose is __________ to carbon dioxide.
    1. oxidized (ans)
    2. reduced (ans)
  4. During aerobic respiration, oxygen is __________ to water.
    1. oxidized (ans)
    2. reduced (ans)
  5. Name the four stages of aerobic respiration. (ans)

18.3A: Glycolysis

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  1. Briefly describe the function of glycolysis during aerobic respiration and indicate the reactants and products. (ans)
  2. State the reactants in glycolysis. (ans)
  3. State the products in glycolysis. (ans)
  4. Does glycolysis require oxygen? (ans)
  5. Is the following statement true or false?

    In eukaryotic cells, glycolysis takes place in the mitochondria. (ans)

  6. Steps 1 and 3 of glycolysis are:
    1. exergonic (ans)
    2. endergonic (ans)
  7. State why one molecule of glucose is able to produce two molecules of pyruvate during glycolysis. (ans)
  8. The two net ATP produced in glycolysis are generated by:
    1. oxidative phosphorylation (ans)
    2. substrate-level phosphorylation (ans)
  9. State the total number and the net number of ATP produced by substrate-level phosphorylation during glycolysis. (ans)
  10. During aerobic respiration, state what happens to the 2 NADH produced during glycolysis. (ans)
  11. During aerobic respiration, state what happens to the two molecules of pyruvate produced during glycolysis. (ans)

18.3B: Transition Reaction

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  1. Briefly describe the function of transition reaction during aerobic respiration. (ans)
  2. State the reactants in the transition reaction. (ans)
  3. State the products in the transition reaction. (ans)
  4. Is the following statement true or false?

    In eukaryotic cells, the transition reaction occurs inside the mitochondria. (ans)

  5. During aerobic respiration, state what happens to the two molecules of Acetyl-CoA produced during the transition reaction. (ans)

18.3C: Citric Acid (Krebs) Cycle

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  1. Briefly describe the function of the citric acid cycle during aerobic respiration. (ans)
  2. State the reactants for the citric acid cycle. (ans)
  3. State the products for the citric acid cycle. (ans)
  4. Is the following statement true or false?

    In eukaryotic cells, the citric acid cycle occurs in the cytoplasm. (ans)

  5. State the total number of ATP produced by substrate-level phosphorylation for each acetyl-CoA that enters the citric acid cycle. (ans)
  6. State the total number of NADH and FADH2 produced for each acetyl-CoA that enters the citric acid cycle. (ans)
  7. During aerobic respiration, state what happens to the NADH and the FADH2 produced during the citric acid cycle. (ans)

18.3D: Electron Transport Chain and Chemisomosis

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  1. Briefly describe the function of the electron transport chain during aerobic respiration. (ans)
  2. Describethe chemiosmotic theory of generation of ATP as a result of an electron transport chain. In the process, describe proton motive force and indicate the function of ATP synthase. (ans)
  3. State whether the following statement is true or false.

    In eukaryotic cells, the electron transport chain is located in the inner membrane of the mitochondria. (ans)

  4. State the final electron acceptor and the end product formed at the end of aerobic respiration. (ans)

18.3E: Theoretical ATP Yield

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  1. Fill in the blanks.

    One molecule of glucose oxidized by aerobic respiration in prokaryotes yields the following:

    Glycolysis:

    _____ net ATP (ans) from substrate-level phosphorylation

    _____ NADH (ans) yields _____ ATP (assuming 3 ATP per NADH) by oxidative phosphorylation (ans)

    Transition Reaction:

    _____ NADH (ans) yields _____ ATP (assuming 3 ATP per NADH) by oxidative phosphorylation (ans)

    Citric Acid Cycle:

    _____ ATP from substrate-level phosphorylation (ans)

    _____ NADH (ans) yields _____ ATP (assuming 3 ATP per NADH) by oxidative phosphorylation (ans)

    _____ FADH2 (ans) yields _____ ATP (assuming 2 ATP per FADH2) by oxidative phosphorylation (ans)

    Total Theoretical Maximum Number of ATP Generated per Glucose in Prokaryotes

    _____ ATP (ans): _____ from substrate-level phosphorylation (ans); _____ from oxidative phosphorylation (ans).

    In eukaryotic cells, the theoretical maximum yield of ATP generated per glucose is _____ to _____. (ans)

18.4: Anaerobic Respiration

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  1. Define anaerobic respiration. (ans)
  2. State the pathways involved in anaerobic respiration. (ans)
  3. State whether the following statement is true or false.

    All organisms are capable of anaerobic respiration. (ans)

18.5: Fermentation

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  1. Define fermentation. (ans)
  2. All the ATP generated by fermentation are produced by:
    1. substrate-level phosphorylation (ans)
    2. oxidative phosphorylation (ans)
  3. State the reactants for fermentation. (ans)
  4. State the products for fermentation. (ans)
  5. Compare the maximum yield of ATP from one molecule of glucose for aerobic respiration and for fermentation. (ans)

18.6: Precursor Metabolites: Linking Catabolic and Anabolic Pathways

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  1. Define precursor metabolites and indicate their importance in metabolism. (ans)

18.7A: Introduction to Photosynthesis

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  1. Organisms that absorb and convert light energy into the stored energy of chemical bonds in organic molecules through a process called photosynthesis best describes:
    1. anoxygenic photoautotrophs (ans)
    2. oxygenic photoautotrophs (ans)
  2. Name the two stages of photosynthesis. (ans)
  3. Define photon. (ans)
  4. Describe what happens when photons of visible light energy strike certain atoms of pigments during photosynthesis and how this can lead to the generation of ATP. (ans)
  5. Fill in the blank.

    The inner membrane of a chloroplast encloses a fluid-filled region called the __________ (ans) that contains enzymes for the light-independent reactions of photosynthesis. Infolding of this inner membrane forms interconnected stacks of disk-like sacs called __________ (ans), often arranged in stacks called __________ (ans).

  6. Name three different types of pigments that play a role in photosynthesis by absorbing light energy. (ans)
  7. State the reactants and the products for photosynthesis and indicate which are oxidized and which are reduced. (ans)

18.7B: Oxygenic Photosynthesis: Light-Dependent Reactions

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  1. Briefly describe the overall function of the light-dependent reactions in photosynthesis. (ans)
  2. Where in the chloroplasts do the light-dependent reactions occur?
    1. In the thylakoids. (ans)
    2. In the stroma. (ans)
  3. The parts of a photosystem that are able to trap light and transfer energy to a complex of chlorophyll molecules and proteins called the reaction center are called _____________. (ans)
  4. In Photosystem II, the electrons lost by chlorophyll P680 molecules are replaced by:
    1. the electrons traveling down the electron transport system of Photosystem I (ans)
    2. the electrons released by the splitting of water (ans)
  5. The primary function of Photosystem II is to produce:
    1. ATP (ans)
    2. NADPH (ans)
  6. Briefly describe how ATP is generated by chemiosmosis during the light-dependent reactions of photosynthesis. (ans)
  7. In Photosystem I, the electrons lost by chlorophyll P700 molecules are replaced by:
    1. the electrons traveling down the electron transport system of Photosystem II (ans)
    2. the electrons released by the splitting of water (ans)
  8. The primary function of Photosystem I is to produce:
    1. ATP (ans)
    2. NADPH (ans)
  9. Involves only Photosystem I and generates ATP but not NADPH. This best describes:
    1. cyclic photophosphorylation (ans)
    2. noncyclic photophosphorylation (ans)

18.7C: Oxygenic Photosynthesis: Light-Independent Reactions

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  1. Briefly describe the overall function of the light-independent reactions in photosynthesis. (ans)
  2. Where in the chloroplasts do the light-independent reactions occur?
    1. In the thylakoids. (ans)
    2. In the stroma. (ans)
  3. State how the light-dependent and light-independent reactions are linked during photosynthesis. (ans)
  4. Briefly describe the following stages of the Calvin cycle:
    1. CO2 fixation (ans)
    2. production of G3P (ans)
    3. regeneration of RuBP (ans)
  5. State the significance of glyceraldehyde-3-phosphate (G3P) in the Calvin cycle. (ans)

18.7D: C4 and CAM Pathways in Plants

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  1. Is the following statement true or false?

    During the C4 pathway for fixing CO2, CO2 from the air combines with ribulose bisphosphate to begin the Calvin cycle. (ans)

  2. Plants that live in very dry condition and, unlike other plants, open their stomata to fix CO2 only at night best describes: (ans)
    1. C4 plants
    2. C3 plants
    3. CAM plants
  3. C4 and CAM pathways evolved for plants that live in _____________________ climates. (ans)
    1. hot, humid
    2. cold, dry
    3. hot, dry