What is the rule called that states only 10% of the energy in one trophic level is transferred to the next, with 90% lost as heat?

• A. Conservation of energy
• B. Secondary consumer
• C. Producer
• D. 10% Rule

Answer: (D)

The main idea is how efficiently energy is passed from one trophic level to the next. In ecosystems, organisms use much of the energy they obtain to fuel metabolic processes, movement, growth, and waste formation, and a large portion is released as heat. Only a small fraction—about 10%—moves up to the next level to support the growth and reproduction of organisms there. This is why energy—and thus biomass—tales drop off quickly at higher trophic levels, and why food chains are relatively short. This specific pattern is described by the 10% rule. It isn’t about conserving energy in general (that’s a universal law) and it isn’t about a particular trophic role like a producer or a consumer; it’s about the proportion that gets transferred between levels.