In an ecosystem, which of the following is unidirectional?

Options

A. Sulphur
B. Organic nutrient
C. Carbon
D. Free energy

Answer

**Step-by-Step Solution:**

1. **Understanding Ecosystem Components**: An ecosystem consists of biotic (living organisms like plants, animals, and microorganisms) and abiotic (non-living elements like sunlight, water, and minerals) components that interact with each other.

2. **Identifying Energy Flow**: In an ecosystem, energy flow is a crucial concept. Energy primarily comes from the sun and flows through the ecosystem in a specific direction.

3. **Direction of Energy Flow**: The flow of energy in an ecosystem is unidirectional, meaning it moves in one direction only. It starts from the sun, which provides solar energy to producers (like plants).

4. **Trophic Levels**: The energy is then transferred from producers to various consumer levels (primary consumers, secondary consumers, and tertiary consumers) through the food chain. This transfer of energy does not reverse; it only moves from one trophic level to the next.

5. **Energy Loss**: As energy moves through the food chain, a significant amount is lost as heat. This loss means that the energy cannot be reused by the organisms in the ecosystem, reinforcing the unidirectional flow.

6. **Identifying the Correct Option**: Among the options provided (sulphur, organic nutrient, carbon, and free energy), we need to determine which one is unidirectional. Sulphur, organic nutrients, and carbon are all recyclable and can be reused in the ecosystem. In contrast, free energy is the only option that flows in one direction.

7. **Conclusion**: Therefore, the correct answer to the question is **free energy**, as it is the only component in the ecosystem that is unidirectional.

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