Enzyme involved in nitrogen assimilation

Options

A. nitrogenase
B. nitrate reductase
C. transferase
D. transaminase

Answer

### Step-by-Step Solution:

1. **Understanding Nitrogen Assimilation**:
- Nitrogen assimilation refers to the process by which plants convert inorganic nitrogen (from nitrates and nitrites) into organic forms (like amino acids).

2. **Identifying the Enzymes**:
- The question provides four enzyme options: nitrogenase, nitrate reductase, transferase, and transaminase.

3. **Role of Nitrate Reductase**:
- Nitrate reductase is the enzyme responsible for the reduction of nitrate (NO3-) to nitrite (NO2-). This is the first step in nitrogen assimilation.

4. **Role of Nitrite Reductase**:
- After nitrate is converted to nitrite, nitrite reductase catalyzes the conversion of nitrite to ammonia (NH3). This ammonia can then be used to synthesize amino acids.

5. **Cofactors Involved**:
- The enzyme nitrate reductase requires molybdenum as a cofactor, while nitrite reductase requires copper and iron.

6. **Conclusion**:
- Among the options provided, the enzyme specifically involved in the process of nitrogen assimilation (the reduction of nitrate to nitrite) is **nitrate reductase**.

### Final Answer:
The enzyme involved in nitrogen assimilation is **nitrate reductase**.

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