IGCSE›Edexcel IGCSE Biology›Mind mapsFeeding RelationshipsEdexcel IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsTrophic levelsProducers make food by photosynthesisPrimary consumers are herbivoresSecondary consumers eat primary consumersTertiary consumers are often top predatorsDecomposers break down dead matter at every levelChains and websFood chain starts with a producerGrass → rabbit → foxFood web links many food chainsWebs are more realistic than single chainsPyramidsNumbers: individuals per level, can be irregularBiomass: mass of living material per levelEnergy transfer: energy per level over timeBiomass and energy are always true pyramidsFeedingfood chains and energy10%Matter transferSome material built into growthSome used in respiration for energySome lost as faeces or not eatenEnergy lossOnly about 10% passes to the next levelMost lost as heat from respirationEnergy used for movementNot all of the organism is eatenChains rarely exceed 4–5 levelsExam tipsArrows point towards the receiver of the energyExplain few levels using the 10% ruleName two loss routes: respiration, movement, undigested