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The aim of this investigation is to investigate a factor that affects the rate of photosynthesis.

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SCIENCE COURSEWORK: PHOTOSYNTHESIS INTRODUCTION The aim of this investigation is to investigate a factor that affects the rate of photosynthesis. Photosynthesis is the word which describes the way which plants feed. Plants can make their own food, unlike animals, that have to find their own source of food. The word equation for photosynthesis is: Sunlight [image002.gif] Carbon dioxide + Water Glucose + Oxygen Chlorophyll The chemical equation for Photosynthesis is: Sunlight [image003.gif] 6CO2 + 6H20 C6H12O6 + 6O2 Chlorophyll During Photosynthesis, Carbon Dioxide and water are the reactants and Glucose and Oxygen are the products. Sunlight energy and chlorophyll are used during the process of photosynthesis. Glucose is stored in the plant as Starch which is an insoluble substance. The outline of the experiment is as follows: A piece of pondweed will be placed into a beaker containing water and sodium bicarbonate; the sodium carbonate will be the source of Carbon dioxide. A lamp will be shined on to the pondweed and the amount of bubbles released from the plant will be counted. The lamp will be adjusted to different distances from the plant to try and obtain different results. VARIABLES EXPERIMENTAL VARIABLE The variable which will be explored in this experiment will be the Light intensity. ...read more.


As the lamp is moved away from the plant, the light intensity decreases. This means that the plant will not be able to break up the bonds of carbon dioxide and water and produce new bonds for the glucose and oxygen at the same rate. This is why the amount of bubbles decreases. METHOD The apparatus required for this experiment is: 1. Pondweed 2. Beaker 3. Funnel 4. Test Tube 5. Plasticene 6. Sodium Bicarbonate 7. Oval: Ruler 8. Lamp 9. Stop Watch [image009.gif] [image010.gif] [image011.gif] Test tube [image012.gif] [image013.gif] Sodium Bicarbonate [image014.gif] [image015.gif] [image016.gif] [image017.gif] Beaker [image018.gif] [image019.gif] [image020.gif] Water Lamp [image021.gif] Funnel [image022.gif] [image023.gif] [image024.gif] 0 cm 100 Plasticene Pondweed Ruler Instructions: 1. Set up the apparatus as shown in the diagram above. 2. Place the lamp directly in front of the plant so it is 10 cm away from the beaker and then turn it on. 3. Wait one minute for the plant to adjust to the level of light timing yourself using the stop watch. 4. Immediately after the minute is over, time yourself for another minute, during which you have to count the amount of bubbles emitting from the plant. 5. After the minute is over, switch the lamp off and record your results. ...read more.


However, the results are fairly close to the line of best fit on the graph so I can say that my results were reasonably reliable. * Some of the bubbles that were emitted from the plant were bigger than others which means that there was a slightly different amount of oxygen in each of the bubbles. This means that the results were not very reliable. Another improvement I could make would be to use a gas syringe instead of counting the bubbles emitting from the plant. This is a more accurate way of measuring the amount of gas being produced by the plant. To improve the accuracy of the results, instead of moving the lamp 10 cm away from the plant each time, I can move the lamp 5 cm away from the plant. Also, instead of doing the experiment until 100 cm, I could do the experiment until 200 cm. To extend this experiment, I could explore other factors that affect the rate of photosynthesis. For example, instead of using light intensity as the variable, I could use the amount of carbon dioxide as the variable. Also, I can explore how different coloured lights affect the way in which plants photosynthesize. To do this, I could place white, red, green and blue coloured filters in front of the lamp and do the experiment with a different coloured filter each time. ...read more.

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