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To measure the rate of photosynthesis in a simple plant such as pondweed, it can be placed within a beaker immersed in water, while a light bulb is shone onto it.

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Science Modular Biology Coursework 1 - Rate of photosynthesis The purpose of this investigation is to investigate the factors which affect the rate of photosynthesis in a plant. I will be conducting various experiments to test my prediction. The basics of photosynthesis involve the plant absorbing sunlight and water, and generating energy. Photosynthesis is a chemical reaction that takes place in the chloroplasts in green plant cells, where light energy is used to convert carbon dioxide and water to glucose and oxygen. The symbol equation for this is: ''CO2 + H2O'' becomes ''C6H12O6+O2'' The sunlight is absorbed into the leaves. The cells within contain chloroplasts, which hold a green pigment called chlorophyll, which is used to combine carbon dioxide and water to produce glucose. The chlorophyll within the chloroplasts also ensures that the green light from the spectrum of light the sun produces is reflected - not absorbed. By doing this and absorbing red and blue light, the leaves appear green. The roots intake water and minerals from the soil they are planted in, and the leaf absorbs carbon dioxide. Chlorophyll absorbs the energy from sunlight which allows water and carbon dioxide to combine and perform a chemical reaction to create glucose. A waste product of this process is oxygen. The formula for the process of photosynthesis is Carbon dioxide + water and sunlight becomes glucose + oxygen. To measure the rate of photosynthesis in a simple plant such as pondweed, it can be placed within a beaker immersed in water, while a light bulb is shone onto it. ...read more.


This would also ensure that the limiting factor would not be the amount of light any more if the rate of photosynthesis happens to remain at a certain speed. When the lamp is moved further away from the plant, the energy the plant intakes from the light is restricted, causing the rate of photosynthesis to decrease. This would effectively make the amount of light the limiting factor. I am going to test the light intensity by varying the distance between the lamp and the plant. The key factors involved in this investigation involve the rate at which oxygen bubbles are released by the plant when the distance between the lamp and the plant is changed. I will keep the plant and the lamp the same during the experiment, and I will change the water for every plant, while varying the distance between the lamp and the plant. In addition, the time which the plant is exposed to the light will remain same throughout. I will also be monitoring the rate at which bubbles appear in the water, and I will measure the volume of oxygen captured in the gas syringe to determine the rate of photosynthesis. First, I will be carrying out a preliminary test for the purpose of defining what I will need to improve for the main test in my investigation. I will now display a table of the results I received: Distance: (cm) ...read more.


If, however, the distance was higher, the energy from the light source would be less concentrated and would take longer to reach the plant, making the plant's rate slow down. As this investigation draws to a conclusion, I can safely say that everything went as anticipated. Naturally, I am pleased with my results as they successfully proved that my prediction was correct. The farthest distance, as expected, caused the plant to have less volume of oxygen within it than it would have had at a closer distance. I am pleased with my decision to attach the apparatus to a clamp, as it is more stable than a person. I am also happy with my decision to repeat the experiment three times, as it proved very helpful in eliminating all anomalies. There were in fact no major aspects which came remotely close to jeapardising the investigation. Everything progressed smoothly. I could point out anomalies easily using my line graph, as any point which is far from the curve of best fit has a high chance of being an anomaly. To improve the experiment the next time I decide I wish to test how the distance from a light source affects the rate of photosynthesis, I will use an increased length of pondweed, and perhaps take more readings and repeat the experiment more times in order to completely wipe out anomalies. I concur by confirming that my hypothesis was proved correct effortlessly. Alexander Karapetian ...read more.

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