Major site of decomposition in the soil and water bodies respectively is

Options

A. Bottom and upper layer
B. Upper and bottom layer
C. Upper and top layer
D. Bottom and top layer

Answer

To answer the question regarding the major sites of decomposition in soil and water bodies, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Decomposition**:
- Decomposition is the process where complex organic matter is broken down into simpler organic and inorganic substances. This process is essential for nutrient cycling in ecosystems.

2. **Identifying the Organisms Involved**:
- Microorganisms such as bacteria and fungi play a crucial role in decomposition. They break down organic matter into simpler forms.

3. **Examining the Process of Decomposition**:
- The decomposition process involves several steps: fragmentation, leaching, catabolism, humification, and mineralization. Each of these steps contributes to the breakdown of organic matter.

4. **Analyzing Decomposition in Soil**:
- In soil, decomposition primarily occurs in the upper layer (or surface layer) where there is a higher concentration of microorganisms. This layer is rich in organic matter and is where most microbial activity takes place.

5. **Analyzing Decomposition in Water Bodies**:
- In aquatic environments, decomposition occurs at the bottom layer (or seabed). Organic matter that sinks to the bottom is broken down by microorganisms present there.

6. **Matching the Findings with Options**:
- Based on the analysis, the major site of decomposition in soil is the upper layer, while in water bodies, it is the bottom layer. Therefore, the correct answer is "upper and bottom layer."

### Conclusion:
The major site of decomposition in the soil is the upper layer, and in water bodies, it is the bottom layer.

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