WAEC - Biology (2007 - No. 40)
The amount of energy passed from one trophic level to the next decreases because
many organisms are present at the first trophic level
many organisms occur at the higher trophic level
more energy is conserved at lower trophic levels
parts of the organisms remain unutilised at each trophic level
Explication
The energy conversion efficiency is higher at lower trophic levels even though a significant amount of energy is lost as heat, waste and other processes. Thus, more energy is conserved at lower trophic levels.