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Investigation of Photosynthesis in Pond weed

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Investigation of Photosynthesis in Pond weed Prediction: I predict that the closer the lamp is to the plant the photosynthesis will be greater. Hypothesis: My prediction is based upon the fact that the closer the lamp is to the plant, the more light will get to it, so more of the plants surface area will be in contact with the light. If this is so, the plant will produce more glucose and oxygen. Photosynthesis is where a plant respires. A plant will take in light, water and carbon dioxide and produces glucose and oxygen. The glucose is used by the plant as food and the oxygen is put back into the environment. So, photo synthesis is very important in the environment otherwise there would be no way of recycling the carbon dioxide waste product from animals back into the useable gas of oxygen. ...read more.


100 ml graduated cylinder to put the pond weed in 2. 300 ml beaker to put the graduated cylinder in 3. Desk lamp 4. Metre ruler 5. A sufficient amount of pond weed to carry out the experiment 6. Stop clock Method: Put a pondweed plant in a beaker of water 250ml full. Put the plant in an inverted measuring cylinder full of water and place it in the beaker of water. Put the lamp at set distance from the beaker with the heat shield between them. Record the oxygen created by the pondweed at 30 second intervals for 2 1/2 minutes. Results Tables The units recorded below are in centimeters cubed (cm3) RESULT SET 1 0 5 10 15 20 25 30 0 0 0 0 0 0 0 0 30 0.4 0.3 0.2 0.1 0.1 0 0 60 0.7 0.5 0.4 0.2 0.1 0 0 90 1.0 0.8 0.5 0.3 ...read more.


In the experiment a trend can be noticed in the results of the oxygen produced. As the distance from the lamp increases, in intervals of 5 cm, a decrease of approximately 0.1cm3 of oxygen is noticed between each interval. It is apparent from the experimental results that the light, of the intensity used, becomes significantly deficient at 30 cm distance, as evidenced by the cessation of generation of oxygen over the experimental time of 2 1/2 minutes. This proves that my original predication was correct. If more of the plants surface area is in contact with the light then the more glucose and oxygen will be created. Evaluation: The experiment is a good example of how the distance between a plant and light can make a difference to photosynthesis. Possibly changing another variable such as temperature could affect the results to find out more. It would possibly make a difference if there was an unlimited supply of carbon dioxide and water. ...read more.

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