External factors affecting the rate of photosynthesis 0.0 / 5 ? BiologyHuman, animal and plant physiologyA2/A-levelCCEA Created by: Football03Created on: 09-03-22 13:47 What are the 3 limiting factors in photosynthesis? -Light intensity -Carbon dioxide concentration -Temperature 1 of 16 What is the actual photosynthetic rate at any one time determined by? Whichever of the factors is least favourable (limiting factor) 2 of 16 What are two key features of limiting factors? -Increasing that factors amount will increase the rate of reaction -Increasing other non-limiting factors will not increase rate of reaction 3 of 16 When does light become limiting? Approaching dusk(nightfall)-photosynthesis can't occur 4 of 16 If light intensity is limiting ,what is affected? The amount of ATP and NADPH produced in the light dependent stage of photosynthesis 5 of 16 What is the atmospheric levels of CO2? Approx. 0.04% 6 of 16 What does increased levels of CO2 lead to? Higher rates of photosynthesis 7 of 16 When is CO2 the limiting factor? On a bright summer day, when light intensity and temperature levels are not limiting 8 of 16 How do people increase their levels of CO2? Burn fossil fuels 9 of 16 What happens if CO2 levels are increased? More available CO2 for the carboxylation of RuBP in the light-independent stage, allowing more GP to be formed 10 of 16 What limits growth in plants in UK? Temperature 11 of 16 What happens if temperature is increased to an optimum? The enzyme-catalysed (rubisco)reactions in light-independent reaction stage of photosynthesis occur at faster rate 12 of 16 What is the optimum temperature for plants? 25 degrees 13 of 16 What would reduce photosynthesis regarding temperature? If its above the optimum; enzyme active site altered and enzyme denatured 14 of 16 What will happen if water is in short supply? (e.g desert) Stomata will close as part of the plant's response in reducing water loss 15 of 16 What will happen to the plant if short of water? The plant will wilt and the orientation of the leaves will change; reducing incident solar radiation and many reactions will slow down 16 of 16
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