The number of trophic levels in a food chain is limited to 4 or 5 because

Options

A. the amount of food produced by producer is limited
B. Consumer's demand is high
C. 90% of the food is lost as heat at each transfer between trophic levels
D. Activity of decomposer is poor

Answer

### Step-by-Step Solution:

1. **Understanding Trophic Levels**:
- A food chain consists of different trophic levels, which include producers (like plants), primary consumers (herbivores), secondary consumers (carnivores that eat herbivores), and tertiary consumers (carnivores that eat other carnivores).

2. **Energy Transfer in Food Chains**:
- In a food chain, energy is transferred from one trophic level to the next. However, this transfer is not efficient.

3. **Energy Loss**:
- It is observed that only about 10% of the energy from one trophic level is passed on to the next level. This means that 90% of the energy is lost at each transfer. This loss occurs due to various factors such as metabolic processes, heat loss, and unconsumed parts of organisms.

4. **Limitation of Trophic Levels**:
- Due to the significant energy loss at each trophic level, there is a limit to how many levels can be sustained in a food chain. Typically, food chains have 4 to 5 trophic levels because there is not enough energy to support more levels.

5. **Conclusion**:
- Therefore, the number of trophic levels in a food chain is limited to 4 or 5 primarily because of the substantial energy loss (90%) that occurs at each level, making it unsustainable to have more levels.

### Final Answer:
The number of trophic levels in a food chain is limited to 4 or 5 because 90% of energy is lost as heat at each transfer between trophic levels.

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