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Photosynthesis Investigation

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Photosynthesis By Alun Tweedale Introduction Photosynthesis occurs only in the presence of light, and takes place in the chloroplasts of green plant cells. Photosynthesis can be defined as the production of simple sugars (glucose) from carbon dioxide and water, which then release sugar and oxygen. Belo is the chemical equation for photosynthesis: light 6CO2 + 6H2O C6H12O6 + 6O2 Photosynthesis will only take place in the presence of chlorophyll. All plants need light in order to photosynthesise (this is proven in many times in experiments) and so without light the plant would die. The light intensity affects the rate of photosynthesis is because as light, falls on the chloroplasts in each leaf and is trapped by the chlorophyll. This makes the energy available for chemical reactions in the plant. Which means as the amount of (sun)light (Light from the bulb) falls on the plant, more energy is absorbed, so more energy is available for the chemical reactions and so the quicker the rate of photosynthesis can occur. I have discovered that there are four ways in which the rate of Photosynthesis can change: 1. Light Intensity 2. Carbon Dioxide availability 3. Water availability 4. Temperature In our experiment we will use the amount of Oxygen produced because we can measure this easily and that it is a by-product of photosynthesis. ...read more.


We also used Sodium Hydrogen Carbonate, which is an irritant, and we should wear safety glasses. Fair Test To keep the test fair we had to keep the volume of the Sodium Hydrogen Carbonate and water the same. Also to keep the test fair we had to keep the time in front of the lamp at 10 seconds. We had to also keep the temperature the same as it affects the rate of photosynthesis and so the volume of oxygen produced. Finally to keep the test fair we had to keep the light colour the same because the chlorophyll absorbs different colours of light at different distances. Limitations We kept the tin of ten seconds because it would get us a sufficient volume of oxygen that could be measured accurately. Results Below are the distances that I had chosen to do and how much oxygen was produced in ten seconds. From these results I put my results into a graph Oxygen produced Against Distance Temperature Light Intensity Distance Concentration of NaHCO3 Oxygen made in 10 secs (mm3) (oC) (lux) (cm) (%) 1 2 3 Adv 20 100 10 2 82 82 82 82 20 70 20 2 58 58 58 58 20 50 30 2 41 41 41 41 20 34 40 2 28 28 28 28 20 23 50 2 20 20 20 20 20 ...read more.


The further away from the plant though it would not have mattered as much. * There could have been a slight difference from when the lamp was switched off and when the stopwatch reached ten seconds because our reaction times are not that quick and in the time that it took for the light to turn off a bubble could have been produced. * Heat generated by the lamp, which could change the temperature, which is one of the properties of photosynthesis. To combat this I could wait for the temperature after each experiment to cool back down to 20oC before I restarted. When there was 100% light intensity, the lamp was 10cm away the pondweed we found the quickest rate of photosynthesis because there was more light energy to use to do the reaction. When there was When there was 11% light intensity, the lamp was 70cm away the pondweed we found the slowest rate of photosynthesis because there was less light energy to use to do the reaction. There were no anomalies. I could have also done other experiments with the other properties that are known to affect the rate of photosynthesis such as carbon dioxide availability, water availability and Temperature. We could have also changed the light colour and the light bulb such as Florissant tubing. ...read more.

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