GCSE›AQA GCSE Biology›Mind mapsPhotosynthesisAQA GCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsThe equationLight energy → chemical energy in glucose6 COX2+6 HX2O→CX6HX12OX6+6 OX2\ce{6CO2 + 6H2O -> C6H12O6 + 6O2}6COX2+6HX2OCX6HX12OX6+6OX2Reaction is endothermic, taking in energyChlorophyll absorbs the lightLight goes above the arrow, not as a reactantLimiting factorsFactor in shortest supply controls the rateLight and CO₂: rate rises then plateausTemperature: enzymes work best around 25-35°CAbove the optimum, enzymes denatureSteep rising line means that factor is limitingInverse square lawHigher Tier: intensity ∝1d2\propto \frac{1}{d^2}∝d21Double the distance → ¼ the intensityTriple the distance → 1/9 the intensityControl distance from the lamp in experimentsPhotosynthesismaking glucose from lightCO2H2OO2Uses of glucoseRespiration releases energyCellulose builds cell wallsStored as starch or oils in seedsMade into amino acids with nitrate ionsStarch used up at night for respirationTwo stagesHigher Tier: light reactions in the thylakoid membranesWater split (photolysis), releasing oxygenLight reactions make ATP and reduced NADPCalvin cycle in the stroma fixes CO₂RuBisCO fixes CO₂ onto RuBPExam tipsBalance the equation: 6 carbons each sideLight is energy, not a chemical reactantControl temperature in light experimentsMeasure rate by counting oxygen bubblesDescribe graphs: rate, then why in limiting factors