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How light intensity affects the rate of photosynthesis

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Introduction

How light intensity affects the rate of photosynthesis The Question With this experiment I'm going to investigate how light affetcs the rate of photosynthesys. Introduction Photosynthesis is the process by which green plants and other organisms transform light into energy. In green plants, light energy is captured by chlorophyll in the chloroplasts of the leaves and used to change water, carbon dioxide, and minerals into oxygen and rich energy organic compounds that are the basis of both plant and animal life. Photosynthesis consists of photochemical and enzymatic reactions. If the photonthesys reaction is acccelerated more organic compounds will be formed and there will be more plant growth. LEAVES The leaf is a part of the plant that is charge of making food. This process is called photosynthesis. The leaf consists of the following parts: Petiole - a thin stalk that connects the blade of the leaf to the plant's stem. These veins are called: Blade - a thin, flat part of the leaf that extends off the end of the petiole. It is green as it contains cholorophyll which is necessary in making the plant's food. ...read more.

Middle

Prediction My prediction, is that the less light that gets to the plant, the slower the rate of photosynthesis . This is because light is the energy that activates the chloroplasts which cause the process called photosynthesis to happen. So I think that the less energy getting to the plant the fewer chloroplasts will be activated meaning that less photosynthesis takes place. Apparatus 1. Test Tube 2. Beaker 3. Canadian Pond Weed 4. 40ml. Water for test tube 5. 150ml. Water for beaker 6. Bicarbonate 7. 4 pieces white cardboard 8. 40 watt light bulb 9. Light bulb stand 10. Sellotape 11.Stop Watch Presentation Method A Test tube was filled with 40ml. of H2O. A short stem of Canadian Pond weed was then put in and the test tube was placed in a beaker containing 150ml. of H2o. Next to this a 40 watt light bulb of in a light bulb holder was placed. To make it a fair test the whole setting was surrounded by white cardboard that stopped any rays of light reaching the plant and for extra accuracy all the lights in the lab were switched off. ...read more.

Conclusion

5 cm. 1 45 5 cm. 2 43 5 cm. 3 46 10 cm 1 40 10 cm 2 39 10 cm 3 38 15 cm 1 40 15 cm 2 30 15 cm 3 35 20 cm 1 20 20 cm 2 26 20 cm 3 23 25 cm 1 18 25 cm 2 16 25 cm 3 13 30 cm 1 9 30 cm 2 5 30 cm 3 7 Graph of results Conclusion As we can see by the results, the rate of photosythesis is affected by the distance between weed and light. We have been able to see a decrease in the rate of bubbles each time the source of light moved further away. This was expected, because as I said earlier on in my prediction, the less energy reaching the chloroplasts the fewer are activated, which makes the food-making process, that involves letting out oxygen, slower. Evaluation On the whole I think that the experiment worked out quite succesfully, for the readings weren�t contradictory to my prediction. We were lucky that the pond weed didn�t die half way through, otherwise we wouldn�t have been able to take accurate readings. If we had used a thermometer we would have able to make sure that the water temperatures didn�t rise. ...read more.

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