GCSE›Edexcel GCSE Biology›Mind mapsFeeding RelationshipsEdexcel GCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTrophic levelsTrophic level = feeding position in a chainProducers make food by photosynthesisBiomass = total mass of living materialEnergy lossLost via respiration, mainly as heatAlso lost by egestion and excretionEnergy is transferred to less useful formsEffect on numbersFewer organisms at higher levelsChains limited to about 4-5 levelsGrass supports many rabbits, few foxesFeedingenergy and biomassBiomass pyramidsAlmost always a true pyramid shapeBiomass decreases at each level upDrawn to scaleEfficiencyEfficiency % = (transferred ÷ available) × 1008000 kJ → 800 kJ8008000×100=10%\frac{800}{8000} \times 100 = 10\%8000800×100=10%Typically about 10% passed onExam tipsSay energy is not fully lost, it becomes heatName the processes: respiration, egestion, excretion