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The effect of light on the rate of photosynthesis.

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The effect of light on the rate of photosynthesis I am going to investigate how the change in light intensity can effect the rate of photosynthesis, and I am going to project light onto pondweed at 5 different distances and seeing how the rate of photosynthesis changes as the distance Changes. I will be able measure the rate of photosynthesis by counting the number of oxygen bubbles leaving the pondweed at the end of the stalk. Prediction I think my results will show that as I bring the projector closer towards the pondweed the rate of photosynthesis will increase causing oxygen bubbles to leave the pondweed because the product of photosynthesis is oxygen and glucose and the oxygen leaves through the Stomata and because the pondweed is under water the leaving oxygen will form into bubbles. CO2 + H2O Oxygen (O2) + Glucose The more I increase the light the faster the reaction will be, and because more light equals faster rate of photosynthesis then this means that light is a limiting factor, CO2 and the temperature are also limiting factors because without one of them the rate of photosynthesis would either stay the same or decrease and so this is why we are going to add Sodium Hydrogen Carbonate which contains CO2 to increase the rate of photosynthesis to make it a better experiment, if we were ...read more.


Another unexpected result was that at 4 at the distance 75 cm the rate of photosynthesis suddenly elevated. In my preliminary experiment I did not take the temperature. Because of the problems in my preliminary experiment it helped me to not make the same mistakes again in my second experiment like using a lamp instead of a projector for example. Changes to Method In my second method I recorded each distance for 2 minutes instead of 4 because 4 minutes took up too much time Andover that longer period of time towards the end of the experiment the rate of photosynthesis would have started to decrease. Also In my second experiment we used a projector instead of a lamp because the light source of the lamp was not strong enough. This time we also increased the amount of Sodium Hydrogen Carbonate to increase the CO2 levels which in turn would increase the rate of photosynthesis. Again this time we did not use a funnel in this experiment because judging from the last experiment it did not make a difference and it was just awkward. My second experiment Equipment I will use: * Projector: To project the light onto the pondweed. * Beaker: To hold the water and the test tube and the Sodium Hydrogen Carbonate. ...read more.


probe, and I would measure it with a computer to be sure that the results are right and not incorrect, and to get the most out of the light from the projector to measure the real amount of oxygen. Overall I think my evidence was of a reasonably good standard because they matched my prediction. I had to repeat my experiment because the first pondweed was not very good were as the second experiments results were good and gave good evidence. The only odd results I had were at 75 cm the rate of photosynthesis was a bit slow because there might have been a bubble trapped in there or there might have been fewer bubbles but the bubbles might have been bigger and so in fact there might have been more oxygen released and only fewer bubbles. I think that my evidence is very reliable because I counted the amount of oxygen bubbles myself and I performed the method accurately. I think my evidence is sufficient to support my conclusion because they match each other almost exactly. To provide additional evidence I think I could do the same experiment except instead of counting the amount of oxygen bubbles leaving the pondweed I could measure the exact amount of oxygen with an oxygen probe. In my experiment the temperature stayed the same so it did not affect the results. ...read more.

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