The Nitrobacter and Nitrocystis

Options

A. (a) oxidise nitrite to nitrate
B. (b) oxidise nitrate
C. (c) reduce nitrite
D. (d) reduce nitrate

Answer

**Step-by-Step Solution:**

1. **Identify the Bacteria**: The question refers to two specific bacteria, Nitrobacter and Nitrocystis.

2. **Understand Their Role**: Both Nitrobacter and Nitrocystis are involved in the nitrogen cycle, specifically in the process of nitrification.

3. **Define Nitrification**: Nitrification is the biological oxidation of ammonia or ammonium to nitrite, followed by the oxidation of nitrite to nitrate.

4. **Identify the Specific Function**: The primary function of Nitrobacter and Nitrocystis is to oxidize nitrite (NO2-) to nitrate (NO3-).

5. **Clarify Other Options**:
- Option A states they oxidize nitrite to nitrate, which is correct.
- Option B states they oxidize nitrate, which is incorrect because nitrate is already in its usable form for plants.
- Option C states they reduce nitrate, which is also incorrect as their role is not to reduce but to oxidize.

6. **Conclusion**: The correct answer is that Nitrobacter and Nitrocystis oxidize nitrite to nitrate.

**Final Answer**: The function of Nitrobacter and Nitrocystis is to oxidize nitrite to nitrate.

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