The fraction of energy lost when an organism proceeds from one trophic level to the next trophic level is

Options

A. 10 percent
B. 20 percent
C. 30 percent
D. 90 percent

Answer

To solve the question regarding the fraction of energy lost when an organism proceeds from one trophic level to the next trophic level, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Trophic Levels**:
- Trophic levels represent the position of organisms in a food chain. The first trophic level consists of producers (plants), the second level consists of herbivores (primary consumers), the third level consists of carnivores (secondary consumers), and the fourth level consists of top carnivores (tertiary consumers).

2. **Energy Transfer in Food Chains**:
- When energy is transferred from one trophic level to the next, not all of the energy is passed on. A significant portion of energy is lost at each level.

3. **The 10% Rule**:
- It is commonly accepted that only about 10% of the energy from one trophic level is transferred to the next. This is known as the "10% Rule" in ecology.

4. **Calculating Energy Loss**:
- If 10% of the energy is transferred to the next trophic level, then the remaining energy that is not transferred is 100% - 10% = 90%.

5. **Conclusion**:
- Therefore, the fraction of energy lost when an organism proceeds from one trophic level to the next is 90%.

### Final Answer:
The fraction of energy lost when an organism proceeds from one trophic level to the next trophic level is **90%**.