Which of the following statements is not correct about energy flow in an ecosystem ?

Options

A. Pyramid of energy is always straight
B. Energy flow is unidirectional
C. Energy flow is cyclic
D. Ecological efficiency is generally `10%`

Answer

To determine which statement is not correct about energy flow in an ecosystem, we will analyze each of the provided statements step by step.

### Step 1: Analyze the First Statement
- **Statement**: The pyramid of energy is always straight.
- **Explanation**: This statement is correct. The pyramid of energy is always upright because energy decreases as it moves from one trophic level to the next. Energy is lost as heat at each step, which results in a decrease in energy available at higher trophic levels.

### Step 2: Analyze the Second Statement
- **Statement**: Energy flow is unidirectional.
- **Explanation**: This statement is also correct. Energy flows in one direction in an ecosystem—from producers to consumers and finally to decomposers. It does not cycle back to the sun or previous trophic levels.

### Step 3: Analyze the Third Statement
- **Statement**: The energy flow is cyclic.
- **Explanation**: This statement is incorrect. Energy flow in an ecosystem is not cyclic; it is unidirectional. While materials like water and nutrients can cycle through the ecosystem, energy is lost as heat and cannot be recycled back into the system.

### Step 4: Analyze the Fourth Statement
- **Statement**: Ecological efficiency is generally 10%.
- **Explanation**: This statement is correct. Ecological efficiency refers to the percentage of energy that is transferred from one trophic level to the next, and it is generally around 10%.

### Conclusion
After analyzing all the statements, the statement that is not correct about energy flow in an ecosystem is: **"The energy flow is cyclic."**

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