A prokaryote responsible for converting ammonia to nitrites is

Options

A. Nitosomonas
B. Nitrobacter
C. Nitrocystis
D. Rhizobium

Answer

To answer the question about which prokaryote is responsible for converting ammonia to nitrites, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Nitrification**:
- Nitrification is a biological process that converts ammonia (NH3) into nitrites (NO2-) and then into nitrates (NO3-). This process is crucial for the nitrogen cycle.

2. **Identifying the Steps of Nitrification**:
- Nitrification occurs in two main steps:
- **Step 1**: Ammonia is converted into nitrite.
- **Step 2**: Nitrite is converted into nitrate.

3. **Recognizing the Bacteria Involved**:
- The first step, which involves the conversion of ammonia to nitrite, is carried out by specific bacteria.
- The bacteria responsible for this conversion is **Nitrosomonas**.

4. **Evaluating the Options**:
- The options provided are:
1. Nitrosomonas
2. Nitrobacter
3. Nitrosystems
4. Riboflavin
- From the options, we can identify that:
- **Nitrosomonas** is the correct answer as it is the prokaryote that converts ammonia to nitrite.
- **Nitrobacter** is involved in the second step (conversion of nitrite to nitrate).
- **Nitrosystems** and **Riboflavin** are not relevant to this process.

5. **Conclusion**:
- Therefore, the prokaryote responsible for converting ammonia to nitrites is **Nitrosomonas**.

### Final Answer:
The prokaryote responsible for converting ammonia to nitrites is **Nitrosomonas**.