Textbook Question
Define oxidation-reduction, and differentiate the following terms:
a. Aerobic and anaerobic respiration
b. Respiration and fermentation
c. Cyclic and noncyclic photophosphorylation
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12. Microbial Metabolism
Redox Reactions
2:27 minutesProblem 10
Textbook Question
Which of the following reactions is an oxidation carried out by A. ferrooxidans?
a. Fe²⁺ → Fe³⁺
b. Fe³⁺ → Fe²⁺
c. CuS→ CuSO₄
d. Fe⁰ → Cu⁰
e. None of the above
Verified step by step guidance1
Step 1: Understand the concept of oxidation in microbiology. Oxidation is the loss of electrons by a molecule, atom, or ion. In chemical terms, this usually corresponds to an increase in oxidation state.
Step 2: Identify the role of Acidithiobacillus ferrooxidans (A. ferrooxidans). This bacterium is known for oxidizing ferrous iron (Fe²⁺) to ferric iron (Fe³⁺), which means it facilitates the reaction where Fe²⁺ loses an electron to become Fe³⁺.
Step 3: Analyze each reaction option to determine which involves oxidation (loss of electrons):
- a. Fe²⁺ → Fe³⁺: Fe²⁺ is oxidized to Fe³⁺ (loss of one electron).
- b. Fe³⁺ → Fe²⁺: Fe³⁺ is reduced to Fe²⁺ (gain of one electron), so this is not oxidation.
- c. CuS → CuSO₄: This is a chemical transformation involving copper sulfide to copper sulfate, which may involve oxidation but is not the classic reaction carried out by A. ferrooxidans.
- d. Fe⁰ → Cu⁰: This suggests elemental iron converting to elemental copper, which is not a typical oxidation reaction by A. ferrooxidans.
Step 4: Conclude that the oxidation reaction carried out by A. ferrooxidans is the conversion of Fe²⁺ to Fe³⁺, corresponding to option a.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Oxidation and Reduction Reactions
Oxidation involves the loss of electrons, while reduction involves the gain of electrons. In redox reactions, one substance is oxidized and another is reduced. Identifying which species loses electrons helps determine the oxidation process.
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Role of Acidithiobacillus ferrooxidans in Iron Oxidation
A. ferrooxidans is a chemolithoautotrophic bacterium that oxidizes ferrous iron (Fe²⁺) to ferric iron (Fe³⁺) as an energy source. This oxidation reaction is central to its metabolism and environmental role in bioleaching and acid mine drainage.
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Electron Transfer in Metal Ion Transformations
Metal ions can undergo redox changes by gaining or losing electrons, altering their oxidation states. For example, Fe²⁺ oxidizes to Fe³⁺ by losing an electron, while Fe³⁺ reduces to Fe²⁺ by gaining an electron. Understanding these changes is key to identifying oxidation reactions.
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