Nitrifying bacteria

Options

A. Oxidize ammonia to nitrates
B. Convert free nitrogen to nitrogen compounds
C. Convert proteins into ammonia
D. Reduce nitrates to free nitrogen

Answer

**Step-by-Step Solution:**

1. **Understanding Nitrifying Bacteria**: Nitrifying bacteria are essential microorganisms involved in the nitrogen cycle. They play a crucial role in converting ammonia into nitrates, which plants can utilize.

2. **Identifying the Process**: The process that nitrifying bacteria are primarily involved in is called nitrification. This process consists of two main steps:
- The first step is the oxidation of ammonia (NH₃) to nitrite (NO₂⁻).
- The second step is the oxidation of nitrite to nitrate (NO₃⁻).

3. **Analyzing the Options**:
- **Option A**: "Oxidize ammonia to nitrate" - This is correct as it describes the primary function of nitrifying bacteria.
- **Option B**: "Convert free nitrogen to nitrogen compounds" - This describes nitrogen fixation, which is not the role of nitrifying bacteria.
- **Option C**: "Convert proteins into ammonia" - This refers to ammonification, which is a different process involving decomposer bacteria.
- **Option D**: "Reduce nitrate to free nitrogen" - This describes denitrification, which is carried out by denitrifying bacteria, not nitrifying bacteria.

4. **Conclusion**: Based on the analysis, the correct answer is **Option A**: "Oxidize ammonia to nitrate."

---