Title: Effect of Light intensity on the rate of Photosynthesis - Biology Notes for IGCSE 2014
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#41 Effect of Light intensity on the rate of Photosynthesis
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Content: This helps to maintain a constant temperature around the pond weed. Place excess sodium bicarbonate (NaHCO3) in the water to give a constant saturated solution of CO2. Place the lamp (the only light source) at distance from the plant. Count the number of oxygen bubbles given off by the plant in 1 minute period. This is the rate of photosynthesis at that particular light intensity. The gas should be checked to prove that it is indeed oxygen - relights a glowing splint. Repeat at different light intensities by moving the lamp to different distances. Photo from passmyexams.co.uk
Graph the results placing light intensity on the x-axis. Explanation
Light energy absorbed by chlorophyll is converted to ATP and H+
At very low light levels the plant will be respiring only not photosynthesising. As the light intensity increases, the rate of photosynthesis increases.