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Measuring the rate of photosynthesis.

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Introduction

Measuring the rate of photosynthesis Plan I am going to investigate the factors that affect the rate of photosynthesis, these factors are: * CO2 * Colour of the light * Temperature * Distance from the lamp to the pondweed * Size of the pondweed * Type of pondweed We could measure and observe the way these factors affect the pondweed by looking at: * The amount of air bubbles formed per minute * The distance from the lamp to the pondweed * The amount of pondweed * The temperature of the water * How much water is lost * The condition of the pondweed I am going to change the different colours of the light by using different pieces of coloured plastic and by doing this I will be observing the amount of air bubbles formed per minute. Apparatus * Lamp * Beaker * Pondweed * Thermometer * Funnel * Test tube * Coloured filters * Stop clock Fair test To make this experiment a fair test I am going to keep the following things the same: * The type of pondweed * The amount of pondweed * The distance from the lamp to the pondweed * The amount of water * The amount of CO2 * The voltage of the lamp * The amount of time used for each piece of coloured plastic Prediction I predict that certain coloured lights will affect the amount of bubbles per minute. ...read more.

Middle

Diagram Coloured filter Test tube Thermometer 10cm Beaker Funnel Pondweed Lamp Result table Colour Amount of bubbles (per min) Average 1st go 2nd go 3rd go Red 68 62 51 60 Blue 33 25 39 32 Green 3 3 3 3 Orange 90 108 111 103 Yellow 117 130 112 120 Conclusion My prediction was incorrect according to my results because I believed that red and blue would be the most intense colour and would produce more air bubbles but according to my results the best colours were yellow and orange because these produced the most air bubbles. I think this had happened because either the plastics are of different thickness or some coloured plastics were letting more light through than they should have been. The colour that stayed the way it was suppose to be was green because that let through very little amount of light according to the amount of air bubbles produced. The experiment needed to be tested at least 3 times each because many of the results varied in a big way, which made you wonder whether our experiment was working. If each piece of plastic had been tested for thickness and length that the results may have been fairer because the plastics wouldn't have been different in any way and we might have got results that followed the colour spectrum and just any pattern. ...read more.

Conclusion

In reference to my prediction, I was incorrect in that the red and blue coloured sheets didn't have the highest rate of photosynthesis, whereas the sheets, which were yellow and orange, resulted in the most bubbles. Each plastic coloured sheet we used had the same time, and variables as the others so we obtained precise results for every test. We did not find anything, which stood out too much from the pattern except that the yellow plastic sheet, when used resulted in more bubbles than the red sheet. This shows that for our experiment chlorophyll absorbed yellow light more easily than red. When the light is absorbed the plant converts it into energy to photosynthesize. The more light energy it receives the better and faster it can do this so when the sheets near the yellow and orange parts of the spectrum are held in front of the pondweed it absorbs the light and can photosynthesize better. If plastic sheets are held up which have a colour near the green part of the spectrum then the light will be transmitted and the plant will not be able to photosynthesize as well, but this did not work as yellow is close to green and it was absorbed the most. In this experiment we have covered the main colours of the visible spectrum and they are sufficient to produce the results that we are looking for. ...read more.

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