Feeding RelationshipsEdexcel GCSE Biology: Flashcards

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Why isn't all energy passed to the next trophic level?

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Why isn't all energy passed to the next trophic level?: Lost via respiration (heat), egestion, excretion.
Define trophic level.: A feeding position in a food chain.
Effect of energy loss on organism numbers?: Numbers decrease at each successive trophic level.
Why do food chains rarely exceed 4-5 levels?: Not enough energy remains to support a further level.
Shape of a pyramid of biomass?: True pyramid — wide base, narrows upward.
Formula for efficiency of energy transfer?: (energy transferred ÷ energy available) × 100.
Producers 5000kJ, consumers 500kJ. Efficiency?: (500÷5000)×100=10%.
Three processes causing energy loss?: Respiration, egestion, excretion.
Main form of lost energy?: Heat.
Define biomass.: Total mass of living material.
Difference: pyramid of biomass vs numbers?: Biomass drawn to scale, almost always true pyramid; numbers can be unusual shapes.
Primary consumers 900kJ, secondary 90kJ. Efficiency?: (90÷900)×100=10%.
Typical efficiency of energy transfer?: Around 10%.
Why are apex predators fewer than producers?: Energy/biomass decreases at each level, limiting numbers supported.