Which of the following statements best explains why ecosystems rarely support food chains with more than four or five trophic levels?
Decomposers compete directly with apex predators for the available biomass in the community.
Only a small percentage of energy (typically about 10%10\%10%) is transferred from one trophic level to the next, with the rest lost as heat, excreted waste, or used in respiration.
Herbivores are extremely efficient at digesting cellulose, which leaves very little organic material available for primary carnivores.
The total biomass of the organisms at the highest trophic level is typically much greater than that of the primary producers.
37 exam-style questions on OCR A A Level Biology Ecosystems. Each one has a worked solution and a mark scheme showing where the marks go.