12. Microbial Metabolism

Fermentation allows a cell to:

a) Recycle NADH to NAD⁺ for glycolysis.

b) Use NADH as a terminal electron acceptor.

c) Reduce NAD⁺ to NADH for glycolysis.

d) Synthesize ATP via ATP synthase.

Which of the following describes a primary function of both lactic acid fermentation and alcohol fermentation?

a) Reduction of NAD⁺ to NADH.

b) Oxidation of NADH to NAD⁺.

c) Reduction of FAD to FADH₂.

d)  Hydrolysis of ATP to ADP.

In which of the steps of aerobic and anaerobic cellular respiration does substrate-level phosphorylation occur?

a) In glycolysis only.

b) In the Krebs cycle only.

c) In the electron transport chain only.

d) In both glycolysis and the Krebs cycle.

e) In both the Krebs cycle and the electron transport chain.

Which of the following statements about NAD⁺ is true?

a) NAD⁺ is reduced to NADH during glycolysis, pyruvate oxidation, and the Krebs cycle.

b) NAD⁺ has more chemical energy than NADH.

c) NAD⁺ donates high energy electrons to the electron transport chain.

d) In the absence of NAD⁺, glycolysis can still function.

Use the following choices to answer questions 7–10.

a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days

b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days

c. both a and b

d. neither a nor b

Which culture produces the most lactic acid?

Use the following choices to answer questions 7–10.

a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days

b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days

c. both a and b

d. neither a nor b

Which culture produces the most ATP?

Use the following choices to answer questions 7–10.

a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days

b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days

c. both a and b

d. neither a nor b

Which culture uses NAD⁺ ?

Use the following choices to answer questions 7–10.

a. E. coli growing in glucose broth at 35℃ with O₂ for 5 days

b. E. coli growing in glucose broth at 35℃ without O₂ for 5 days

c. both a and b

d. neither a nor b

Which culture uses the most glucose?

For questions 1–4, answer whether

a. the process takes place under aerobic conditions.

b. the process takes place under anaerobic conditions.

c. the amount of oxygen doesn’t make any difference.

Denitrification

For questions 1–4, answer whether

a. the process takes place under aerobic conditions.

b. the process takes place under anaerobic conditions.

c. the amount of oxygen doesn’t make any difference.

Nitrogen fixation

For questions 1–4, answer whether

a. the process takes place under aerobic conditions.

b. the process takes place under anaerobic conditions.

c. the amount of oxygen doesn’t make any difference.

Methane production

Use the following choices to answer questions 6–8:

a. aerobic respiration

b. anaerobic respiration

c. anoxygenic photosynthesis

d. oxygenic photosynthesis

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Use the following choices to answer questions 6–8:

a. aerobic respiration

b. anaerobic respiration

c. anoxygenic photosynthesis

d. oxygenic photosynthesis

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Describe an example of bioconversion. What metabolic processes can result in fuels?

Which one of the following is not a fuel produced by microorganisms?

a. algal oil

b. ethanol

c. hydrogen

d. methane

e. uranium