At that point the two factors that are kept constant will act as limiting factors and they will be limiting the further increase in rate of photosynthesis.
Method: In this experiment we kept temperature as an independent variable. We cut a piece of elodea and kept it in a beaker of water and anchored it with a paper clip. We placed the lamp 7cm away from the beaker and the lamp was kept at this point throughout the experiment. In order to keep the concentration of CO2 constant we assumed that the CO2 in the water in the beaker remained same throughout the experiment. We changed the temperature of the experiment by changing the temperature of the water in the beaker. We obtained hot water in the beaker by pouring hot water from the kettle in the beaker and we obtained cold water by adding ice to the beaker. We measured the rate of photosynthesis by measuring the rate of oxygen given off by the elodea. In order to measure the volume of air given off we used a photosynthometer. In order to prevent bubbles to appear in the tubing of photsynthometer we kept the tubing in the water.
We started out experiment with initial temperature of 40 Â°C. We used a thermometer to ensure that the temperature of water in the beaker was 40 Â°C and then placed elodea that has previously kept in dark into the beaker. We used a piece of elodea that was previously kept in the dark because this ensured that the plant had not been previously photosynthesing and it avoided us having unfair results. Once we placed elodea in the beaker we immediately started noting the time it took for 5mm3 of air to be trapped in photosynthometer.
The average time taken at 40 Â°C was calculated and it was noted as 6.5 minutes. The experiment was repeated at different temperatures like 15 Â°C, 20Â°C, 30 Â°C. To ensure constant temperature was maintained during each experiment a thermometer was placed in the