Reduction is the term used when conversion of ……… takes place

Options

A. nitrate to nitrite
B. nitrite to nitrate
C. ammonia to nitrogen
D. All of the above

Answer

**Step-by-Step Solution:**

1. **Understanding Reduction**: The term "reduction" in biological processes refers to a chemical reaction where a molecule gains electrons or hydrogen, or loses oxygen. This process is crucial in various metabolic pathways, including nitrogen metabolism.

2. **Identifying the Options**: The options provided are:
- A) Nitrate to nitrite
- B) Nitrite to nitrate
- C) Ammonia to nitrogen
- D) All of the above

3. **Analyzing Each Option**:
- **Option A (Nitrate to nitrite)**: This is a reduction process where nitrate (NO3-) is converted to nitrite (NO2-) using the enzyme nitrate reductase. This reaction involves the gain of electrons and is a key step in the nitrogen cycle.
- **Option B (Nitrite to nitrate)**: This is an oxidation process, not a reduction. It is part of nitrification where nitrite is converted back to nitrate, which involves the loss of electrons.
- **Option C (Ammonia to nitrogen)**: This process is related to nitrogen fixation and is not a reduction in the context of the nitrogen cycle. Instead, it involves the conversion of nitrogen gas to ammonia, which is a different process.
- **Option D (All of the above)**: Since not all options represent reduction, this cannot be correct.

4. **Conclusion**: The only correct reduction process from the options is A) Nitrate to nitrite. Therefore, the answer to the question is that reduction is the term used when the conversion of nitrate to nitrite takes place.

**Final Answer**: A) Nitrate to nitrite

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