GCSE›AQA GCSE Biology›Mind mapsRespirationAQA GCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsAerobicHappens in the mitochondriaGlucose + oxygen → CO₂ + waterCX6HX12OX6+6 OX2→6 COX2+6 HX2O\ce{C6H12O6 + 6O2 -> 6CO2 + 6H2O}CX6HX12OX6+6OX26COX2+6HX2OExothermic, releasing lots of energyMost efficient: glucose fully oxidisedUses of energyMovement through muscle contractionBuilding larger molecules such as proteinsKeeping body temperature stable, around 37°CAnaerobicNo oxygen needed, in the cytoplasmReleases much less energyAnimals: glucose → lactic acidPlants and yeast: glucose → ethanol + CO₂Lactic acid builds up and causes fatigueRespirationreleasing energy from glucoseO2CO2Oxygen debtExtra oxygen needed to break down lactic acidHigher Tier: liver turns lactic acid back into glucoseBreathing and heart rate stay elevated afterwardsBigger debt after harder, longer exerciseDuring exerciseHeart rate rises from 60-80 bpmBreathing rate rises from 12-20 per minuteTidal volume rises: deeper breathsMuscles need more oxygen and glucoseMore CO₂ is made and must be removedExam tipsState mitochondria and exothermic for aerobicLactic acid in animals, ethanol in plants and yeastExplain why heart rate rises, not just that it doesRespirometer needs an absorbent such as soda lime