Photosynthesis- Part 2 0.0 / 5 ? BiologyCellular processesA2/A-levelOCR Created by: laelle1479Created on: 11-01-17 11:02 What are limiting factors? Factors that affect the rate of photosynthesis 1 of 21 What 5 factors affect the rate of photosynthesis? Light intensity, amount of CO2 amount of water, temperature, availability of chlorophyll, electron carriers, enzymes 2 of 21 What limits the rate of photosynthesis? The factor that's present in the least favourable amount (limiting factor0 3 of 21 What unit measures the rate of photosynthesis? Lux 4 of 21 Unit for light intensity? Arbitrary units (a.u.) 5 of 21 What is light intensity? The level of light 6 of 21 Why is light needed for photosynthesis? Provides energy for the 1st stage that produces ATP and NADP for the 2nd stage) & opens the stoma for the transpiration of water for photolysis 7 of 21 What happens to the GP concentration when the light intensity is dim? GP levels increase 8 of 21 Why? They can't be reduced due to low levels of NADPH and ATP 9 of 21 What happens to the concentration of TP? They decrease 10 of 21 Why? Because GP isn't reduced 11 of 21 What happens to the concentration of RuBP? It decreases 12 of 21 Why? Because GP isn't being reduced and RubP isn't being regenerated from TP 13 of 21 What happens if the concentration of carbon dioxide falls below 0.01%? RuBP can't accept it and accumulates, GP and thus TP can't be made 14 of 21 What are the limitations of measuring the rate of photosynthesis based on how much O2 is produced? Some of the O2 is used by the plant for respiration + there may be some dissolved nitrogen in the gas collected 15 of 21 What apparatus can be used to measure the factors affecting photosynthesis? A photosynthometer 16 of 21 Why is the calvin cycle senstitive to temperature? It involves many enzyme-catalysed reactions 17 of 21 In what conditions does the rate of photosynthesis increase? From low temperatures to 25-30C; if there's enough light, water and CO2 18 of 21 What happens in the calvin cycle at temperatures above 30C? Growth rates decline due to photorespiration: oxygen competes with carbon dioxide for Rubisco's active site 19 of 21 What happens in the calvin cycle at temperatures above 45C? The enzymes involved in photosynthesis may denature 20 of 21 What is water stress? The condition a plant experiences when water supply becomes limited 21 of 21
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