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 to increase the temperature as well the rate of photosynthesis would increase, if one of the three were lacking the rate of photosynthesis would either stay the same or decrease.

Graph of Prediction

Why I make this Prediction

If we were to increase the light even more, the rate of photosynthesis would not increase because there is not enough heat or Carbon Dioxide. However at the start of the experiment because there is enough Carbon Dioxide and the temperature is high enough and because the light intensity is increasing the closer the projector gets to the pondweed the more the rate of photosynthesis increases. When we project light onto the pondweed the rate of photosynthesis increases because the chlorophyll absorbs the light and with Carbon Dioxide and H2O photosynthesis occurs producing Glucose and oxygen and so the oxygen leaves the pondweed through the Stomata and because it is under water it forms oxygen bubbles. So the prediction graph levels off at the end because there is not enough Carbon Dioxide and the temperature is not high enough.

Fair test factors

To make it a fair test I will make sure that:

* The light source is the same, because then the light intensity will be the same (except at different distances) otherwise a different light source would make the results incorrect.
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* To make sure the temperature stays the same, this way the results will not change drastically, for example if the temperature dropped considerably then the rate of photosynthesis would decrease. To make sure the temperature does not change we will leave a thermometer in the beaker so as if we notice that the temperature is increasing or decreasing we can do something about it.

* To make sure I put in the same amount of Sodium Hydrogen Carbonate. Because more Sodium Hydrogen Carbonate would increase the rate of photosynthesis and too little of it would stop ...

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