All the following are correct statement about a small pond ecosystem, except :

Options

A. This is fairly a self-sustainable unit.
B. All the four basic components of an ecosystem are well exhibited
C. The abiotic component is the water with all the dissolved organic and inorganic substances and the rich soil deposit at the bottom of the pond.
D. This ecosystem performs all functions of any ecosystem except the unidirectional flow of energy.

Answer

To solve the question regarding the statements about a small pond ecosystem, we will evaluate each statement one by one to identify the incorrect one.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that a small pond ecosystem is a purely self-sustainable unit.
- **Analysis:** A small pond ecosystem is indeed largely self-sustainable due to the interactions between its biotic and abiotic components. It can maintain its balance and support life through processes like photosynthesis, decomposition, and nutrient cycling.
- **Conclusion:** This statement is correct.

2. **Evaluate the Second Statement:**
- The second statement asserts that all four basic components of the ecosystem are well activated.
- **Analysis:** The four basic components of an ecosystem are producers, consumers, decomposers, and abiotic factors. In a pond ecosystem, these components are present and interact effectively, contributing to the overall functioning of the ecosystem.
- **Conclusion:** This statement is also correct.

3. **Evaluate the Third Statement:**
- The third statement describes the abiotic component as water with all the dissolved organic and inorganic substances and the rich deposit at the bottom of the pond.
- **Analysis:** This is an accurate description of the abiotic components of a pond ecosystem. Water serves as the primary abiotic factor, and the sediments at the bottom contribute to the ecosystem's nutrient supply.
- **Conclusion:** This statement is correct as well.

4. **Evaluate the Fourth Statement:**
- The fourth statement claims that the ecosystem performs all the functions of the ecosystem except the unidirectional flow of energy.
- **Analysis:** In any ecosystem, including a pond, energy flows in a unidirectional manner—from producers to consumers and then to decomposers. This is a fundamental principle of ecology. Therefore, this statement is incorrect because the unidirectional flow of energy is indeed a function of the ecosystem.
- **Conclusion:** This statement is incorrect.

### Final Answer:
The incorrect statement about a small pond ecosystem is the fourth statement: "The ecosystem performs all the functions of the ecosystem except the unidirectional flow of energy."

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