The flow of energy in an ecosystem is

Options

A. unidirectional
B. bidirectional
C. multidirectional
D. cyclic

Answer

### Step-by-Step Solution:

1. **Understanding Energy Flow in Ecosystems**: Energy flow in an ecosystem refers to how energy is transferred from one trophic level to another. It begins with the sun, which provides energy to producers (plants).

2. **Producers and Energy Capture**: Producers, such as plants, capture solar energy through photosynthesis. They convert sunlight into chemical energy, which is stored in the form of glucose.

3. **10% Law**: According to the 10% law, only about 10% of the energy from one trophic level is passed on to the next. For example, if producers capture 10,000 joules of energy, only 1,000 joules will be available to primary consumers (herbivores).

4. **Energy Transfer Between Trophic Levels**:
- **Producers (1st Trophic Level)**: 10,000 joules
- **Primary Consumers (2nd Trophic Level)**: 1,000 joules (10% of 10,000 joules)
- **Secondary Consumers (3rd Trophic Level)**: 100 joules (10% of 1,000 joules)
- **Tertiary Consumers (4th Trophic Level)**: 10 joules (10% of 100 joules)

5. **Pyramid of Energy**: The energy pyramid is always upright, meaning that energy decreases as you move up the trophic levels. This is because energy is lost at each transfer, primarily as heat.

6. **Unidirectional Flow**: Energy flows in one direction—from producers to various levels of consumers. It does not cycle back like nutrients do in an ecosystem.

7. **Conclusion**: The flow of energy in an ecosystem is unidirectional and follows the 10% law, resulting in an upright energy pyramid.

### Final Answer:
The flow of energy in an ecosystem is unidirectional and follows the 10% law, resulting in an upright energy pyramid.

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