Florida Biology EOC Practice Test

What percentage of energy passes from one trophic level to the next in an ecosystem?

1. 10%

2. 25%

3. 50%

4. 75%

The correct answer is: 10%

In an ecosystem, approximately 10% of the energy available at one trophic level is transferred to the next level. This concept is based on the energy pyramid, which illustrates how energy decreases as it moves through different levels of the food chain. The vast majority of energy is lost at each level due to various factors such as metabolic processes, heat loss, and the energy used for growth, reproduction, and movement. For instance, producers (such as plants) photosynthesize and capture solar energy, but only about 10% of that energy is converted into biomass, which can then be consumed by primary consumers (herbivores). When primary consumers are eaten by secondary consumers (carnivores), again, around 10% of the energy they gained from the producers is passed on. This pattern continues up the food chain, leading to the rule of 10%, which illustrates how energy diminishes as it moves up trophic levels. Thus, the understanding of energy transfer in ecosystems hinges on this 10% rule, making it clear why this answer is correct.