A supplied energy-transfer assumption

A fictional ecology exercise gives annual net primary production of 12000 energy units for a defined patch and instructs learners to assume ten-percent transfer between each consecutive trophic level. The exercise is a simplified model rather than a field measurement of every feeding relationship. A learner calculates energy available at the next two levels and then claims that every real food web must have exactly those efficiencies. Another learner treats energy as if it cycles back unchanged in the same way as nitrogen atoms. The task is to use the stated numerical model correctly while explaining its limits and distinguishing energy transfer from material cycling.