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The effect of varying light intensity on the rate of Photosynthesis of the aquatic plant Elodea.

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Introduction

The effect of varying light intensity on the rate of Photosynthesis of the aquatic plant Elodea Mubasher 10B Data Analysis Distance of lamp Length of bubble after 5 minutes (mm) Average length Light Intensity from plant (cm) of bubble (Lux) 5 29 49 52 56 56 59 50.17 4000 10 12 21 22 27 26 30 23 1000 15 9 9 10 12 14 13 11.17 444.4 30 2 3 3 2 5 4 3.17 111.1 50 1 2 2 1 1 2 1.50 40 Light intensity workings: 1/distance2 * 100,000 = 1/52 * 100,000 = 1/25 * 100,000 = 4000 For all the rest, workings are the same. Graph See other sheet Conclusion The pattern shown on the above graph shows that as you increase the light intensity the rate of photosynthesis increases at a decreasing rate. Sunlight + Chlorophyll Carbon dioxide + Water Oxygen + Glucose + Energy These results tell me that an increase in light intensity does increase the rate of photosynthesis. The gradual decrease in the rate of photosynthesis (the straightening of the curve) can be linked to the other factors limiting the rate of photosynthesis. ...read more.

Middle

This is because the light is increasing constantly. However the rate of photosynthesis decreases at the end because the chlorophyll has got enough energy but needs more carbon dioxide to combine with water to increase the rate. This part of the graph shows me that the increase in rate is proportional to the increase in light intensity (i.e. a straight line) and I can show this by taking some readings from the graph (See other Sheet) Evaluation I have identified two anomalous results which are highlighted on the table in red. There were errors in the experiment which could have caused this. Some human errors and some errors we can't help. Measuring the distance from the filament to the plant each time, measuring the length of the bubble and timing are human errors Also when the lamp is close to the plant it gives it heat energy as well. This will increase the rate of photosynthesis so our bubble will become bigger. This only really affects the plant when is close to it. ...read more.

Conclusion

Give it two minutes to settle and adjust to the new light intensity. 5) Start the stopwatch and count the number of bubbles produced in one minute. 6) Repeat 5 times 7) Repeat steps 4, 5 and 6 with distances 30cm, 15cm, 10cm and 5cm. Distance of lamp Amount of bubbles after 1 minute Average amount Light Intensity from plant (cm) of bubbles (Lux) 5 10 15 30 50 A glass wall is kept in front of the beaker so no heat from the lamp can affect the rate of Photosynthesis. After getting all the data I would plot some of the data on a graph. I would plot the amount of bubbles with the light intensity. Then I could find out how light intensity affects Elodea with greater accuracy. To get extra information about the rate of photosynthesis, I could try to relate some of the other limiting factors to the same experiment, as well as investigating them on their own. It could also be worthwhile to explore the effects of coloured lights on the rate of photosynthesis, which could lead to other experiments such as whether or not other types of light, such as fluorescent lights or halogen lights, would have a different effect on the rate of photosynthesis. ...read more.

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