In nitrogen cycle, which of the following plays an important role ?

Options

A. Rhizopus
B. Nitrobacter
C. Mucor
D. Claviceps

Answer

To solve the question regarding which organism plays an important role in the nitrogen cycle, we can follow these steps:

### Step 1: Understand the Nitrogen Cycle
The nitrogen cycle is a biogeochemical cycle that describes the transformation of nitrogen and nitrogen-containing compounds in nature. It involves several processes, including nitrogen fixation, nitrification, denitrification, and ammonification.

**Hint:** Familiarize yourself with the key processes in the nitrogen cycle, such as nitrogen fixation and nitrification.

### Step 2: Identify Key Organisms Involved
In the nitrogen cycle, specific organisms play crucial roles:
- **Nitrogen-fixing bacteria** (like Rhizobium) convert atmospheric nitrogen (N₂) into ammonia (NH₃).
- **Nitrifying bacteria** (such as Nitrosomonas and Nitrobacter) convert ammonia into nitrites (NO₂⁻) and then into nitrates (NO₃⁻).

**Hint:** Remember the roles of different bacteria in the nitrogen cycle, especially those involved in nitrogen fixation and nitrification.

### Step 3: Analyze the Options
Given the options, we need to determine which organism is associated with the nitrogen cycle:
- **Rhizobium**: A nitrogen-fixing bacterium that helps convert atmospheric nitrogen into ammonia.
- **Nitrobacter**: A nitrifying bacterium that converts nitrites into nitrates.
- **Fungi (like Rhizopus, Mucor, and Claviceps)**: Generally not involved in the nitrogen cycle as they are mostly saprophytic and do not fix nitrogen.

**Hint:** Focus on the bacteria mentioned, as they are key players in the nitrogen cycle.

### Step 4: Determine the Correct Answer
From the analysis, both Rhizobium and Nitrobacter are important in the nitrogen cycle. However, if the question specifies one organism, it is essential to choose the one that is primarily known for its role in nitrogen fixation (Rhizobium) or nitrification (Nitrobacter).

**Hint:** If the question asks for the most significant contributor to the nitrogen cycle, consider which process is being highlighted—fixation or nitrification.

### Conclusion
Based on the roles outlined, the correct answer to the question about which organism plays an important role in the nitrogen cycle is **Nitrobacter**, as it is specifically mentioned in the context of converting ammonia to nitrates.

**Final Answer:** Nitrobacter plays an important role in the nitrogen cycle.