Which one of the following is not a functional unit of an ecosystem

Options

A. Decomposition
B. Productivity
C. Stratification
D. Energy flow

Answer

To determine which of the following is not a functional unit of an ecosystem, we need to analyze each option provided: decomposition, productivity, stratification, and energy flow.

### Step-by-Step Solution:

1. **Understanding Decomposition**:
- Decomposition is a process carried out by decomposers (like bacteria and fungi) that breaks down dead organic matter into simpler substances. This process recycles nutrients back into the ecosystem, making it a vital functional unit.

2. **Understanding Productivity**:
- Productivity refers to the rate at which energy is produced in an ecosystem, primarily through photosynthesis by plants (producers). It is a measure of the biomass generated in an ecosystem and is essential for the sustenance of all other trophic levels.

3. **Understanding Energy Flow**:
- Energy flow describes how energy moves through an ecosystem, from producers to consumers and eventually to decomposers. This flow is crucial for maintaining the ecosystem's structure and function.

4. **Understanding Stratification**:
- Stratification refers to the vertical layering of different species in an ecosystem, particularly in forests, where different species occupy different heights. While it describes the organization of species, it does not directly contribute to the functioning of the ecosystem in the same way that decomposition, productivity, and energy flow do.

5. **Conclusion**:
- Based on the definitions and roles of each option, stratification is not considered a functional unit of an ecosystem. Therefore, the correct answer is **stratification**.

### Final Answer:
Stratification is not a functional unit of an ecosystem.

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