The non-symbiotic `N_(2)` fixer is

Options

A. Anabaena
B. Rhizobium
C. Azotobactor
D. Azolla

Answer

To answer the question "The non-symbiotic N₂ fixer is," we can follow these steps:

### Step 1: Understand Nitrogen Fixation
Nitrogen fixation is the process of converting atmospheric nitrogen (N₂) into ammonia (NH₃), which can be utilized by plants. This process is crucial for plant nutrition and growth.

### Step 2: Differentiate Between Symbiotic and Non-Symbiotic Nitrogen Fixation
There are two main types of nitrogen-fixing organisms:
- **Symbiotic Nitrogen Fixers**: These are bacteria that form a mutualistic relationship with plants. They live in association with the plant roots and help in nitrogen fixation. An example of this is Rhizobium, which associates with legumes.
- **Non-Symbiotic Nitrogen Fixers**: These are free-living bacteria that do not form a relationship with plants. They can fix nitrogen independently. Examples include Anabaena and Nostoc.

### Step 3: Identify the Non-Symbiotic Nitrogen Fixer
From the examples provided, Anabaena and Nostoc are both non-symbiotic nitrogen fixers. They are cyanobacteria that can fix nitrogen in aquatic environments or soil.

### Step 4: Conclude the Answer
Based on the information, the correct answer to the question "The non-symbiotic N₂ fixer is" is **Anabaena**.

### Final Answer:
The non-symbiotic N₂ fixer is **Anabaena**.

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