Question

4) Colon bacteria that produce H2S produce actually do so by using anaerobic respiration pathway.

5. Which of the following can be the carbon source for H2S production using the metabolic pathway you identified in your answer to Question #4?

a. hydrogen gas (H2)

b. elemental sulfur (S)

c. carbon dioxide (CO2)

d. glucose (C6H12O6)

6. This carbon source identified in your answer to Question #5 is an____ molecule. a. organic b. inorganic

7. The electron donor for H2S production using the metabolic pathway identified in Question #4 is ____(hydrogen gas/elemental sulfur/carbon dioxide/glucose), which is in a fully ____(oxidized or reduced) state in its role as an electron donor.

8. The electron acceptor for the H2S production using the metabolic identified in Question #4 is ____(hydrogen gas/elemental sulfur/carbon dioxide/glucose), which is an ____(organic or inorganic) molecule that is in a fully ____(oxidized or reduced) state in its role as the final electron acceptor.

9. Some colon bacteria can produce methane (CH4) using the same metabolic pathway you identified in Question #4. The carbon source and electron source are the same for both H2S and CH4 production, but for methane production, the final electron acceptor is _____.

a. hydrogen gas (H2)

b. elemental sulfur (S)

c. carbon dioxide (CO2)

d. glucose (C6H12O6)

10. The final electron acceptor identified in Question #9 is an ____(organic or inorganic) molecule in a fully ____(oxidized or reduced) state.

11. Some other colon prokaryotes are able to generate methane (CH4) using a different metabolic pathway than the one you identified in Question #4. These prokaryotes can use which of the following metabolic pathways?

a. aerobic respiration

b. anaerobic respiration

c. photosynthesis

d. autotrophic methanogenesis

12. The carbon source for methane (CH4) production using the metabolic pathway identified in Question #11 is:

a. hydrogen gas (H2)

b. elemental sulfur (S)

c. carbon dioxide (CO2)

d. glucose (C6H12O6)

13. The electron donor for methane (CH4) production using the metabolic pathway identified in Question #11 is ____(hydrogen gas/elemental sulfur/carbon dioxide/glucose), which is an ____(organic or inorganic) molecule that is in a fully ____(oxidized or reduced) state in its role as an electron donor.

14. The final electron acceptor for methane (CH4) production using the metabolic pathway identified in Question #11 is:

a. glucose (C6H12O6)

b. carbon dioxide (CO2)

c. elemental sulfur (S)

d. hydrogen gas (H2)

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Answer 1

• Anaerobic respiration, the carbon source is glucose.
• Oxygen is not used for to oxidize glucose and generate energy.
• Instead of oxygen other substances or molecules which are in oxidized state, are used as electron or hydrogen acceptor.
• If H₂S is released, then anaerobic breakdown of glucose occurs.
• Glucose is an organic compound forming part of living cells. It is composed of carbon, hydrogen and oxygen, and undergoes oxidation-reduction reactions during metabolic activities.
• During respiration glucose act as electron donor and is oxidized and Sulfur acts as acceptor of electrons.
• Thus, Sulfur is reduced to release H₂S.
• If methane is produced, CO₂ is used as electron acceptor. CO₂ is reduced to generate methane.
• CO₂ may also be used as inorganic source of carbon during autotrophic reactions to generate organic molecules like glucose. If methane generated during the autotrophic process, then the metabolic pathway is autotrophic methanogenesis.

Answers:

5. d. Glucose

6. a. Organic

7. Glucose, reduced

8. Elemental Sulfur, Oxidized state

9. c. CO₂

10. inorganic, Oxidized state

11. d. autotrophic methanogenesis.

12. c. CO₂

13. Hydrogen gas, inorganic, reduced

14. b. carbon dioxide, CO₂