Give the functions of nitrogen in the atmosphere.

Explanation

### Step-by-Step Solution:

1. **Understanding the Composition of the Atmosphere**:
- The atmosphere is composed of various gases, with nitrogen being the most abundant, making up about 78% by weight.

2. **Role of Nitrogen in Plant Metabolism**:
- Nitrogen is essential for plants as it is a key component of amino acids, proteins, and nucleic acids. Plants require nitrogen for their basic metabolic processes.
- Nitrogen fixation occurs either through root nodules in certain plants (like legumes) or through direct absorption from the atmosphere.
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