Process of nitrification and nitrate assimilation are

Options

A. Oxidation and reduction respectively
B. Reduction and oxidation respectively
C. Both are oxidation
D. Both are reduction

Answer

### Step-by-Step Solution:

1. **Define Nitrification**:
- Nitrification is the biological process that converts ammonia (NH3) into nitrites (NO2-) and then into nitrates (NO3-). This process is crucial for the nitrogen cycle as it makes nitrogen available to plants in a usable form.

2. **Nitrification Reaction**:
- The overall reaction for nitrification can be summarized as:
\[ 2NH3 + 3O2 \rightarrow 2NO2- + 2H+ + 2H2O \]
- This reaction shows that ammonia is oxidized, meaning it loses electrons, and oxygen is consumed in the process.

3. **Define Nitrate Assimilation**:
- Nitrate assimilation is the process by which plants absorb nitrates from the soil and convert them into organic compounds, primarily amino acids. This process is essential for plant growth and development.

4. **Nitrate Assimilation Reaction**:
- The reaction for nitrate assimilation can be represented as:
\[ 2NO2- + O2 \rightarrow 2NO3- \]
- After absorption, nitrates are reduced to ammonia through a process known as reductive amination, which is then used to synthesize amino acids.

5. **Identify the Nature of Each Process**:
- Nitrification is characterized as an **oxidation reaction** because it involves the conversion of ammonia to nitrate, which involves the loss of electrons.
- Nitrate assimilation, on the other hand, is characterized as a **reduction reaction** because it involves the conversion of nitrates to ammonia, which involves the gain of electrons.

6. **Conclusion**:
- Therefore, the processes of nitrification and nitrate assimilation can be summarized as:
- Nitrification: **Oxidation**
- Nitrate Assimilation: **Reduction**

### Final Answer:
The processes of nitrification and nitrate assimilation are oxidation and reduction, respectively.

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