Which of the following can use elemental nitrogen as their nitrogen source

Options

A. anabaena
B. Nitrobacter
C. Nitrosomonas
D. All of the above

Answer

To determine which of the following can use elemental nitrogen as their nitrogen source, we will analyze each option provided:

1. **Understand the options**: The options given are:
- A) Anabena
- B) Nitrobacter
- C) Nitrosomonas
- D) Olifetava

2. **Identify the characteristics of each organism**:
- **Anabena**: This is a genus of cyanobacteria known for its ability to fix nitrogen. It can utilize elemental nitrogen (N2) from the atmosphere and convert it into a form that can be used by plants.
- **Nitrobacter**: This is a genus of bacteria involved in the nitrification process. It oxidizes nitrite to nitrate and does not use elemental nitrogen directly.
- **Nitrosomonas**: This is another genus of bacteria that also participates in nitrification, converting ammonia to nitrite. Like Nitrobacter, it does not use elemental nitrogen.
- **Olifetava**: This option is not widely recognized in the context of nitrogen fixation or utilization, and it may be a typographical error or a less-known organism.

3. **Determine which organism uses elemental nitrogen**:
- Among the options, **Anabena** is the only organism that can utilize elemental nitrogen as its nitrogen source. It performs nitrogen fixation, converting atmospheric nitrogen into ammonia, which can then be used by plants.

4. **Conclusion**: Based on the analysis, the correct answer is **Option A: Anabena**.