Photosynthesis: Light and Plant

ESS Internal Assessment: Lab Report Aim: The aim is to measure the rate of photosynthesis of an aquatic plant (Cabomba species) at different light intensities. Hypothesis: If the distance between the lamp and the plant increases the rate of photosynthesis decreases because the plant requires light for photosynthesis to occur. Variables: Independent: The independent variable for this experiment is light intensity. In each trial the distance between the plant and the lamp will be increased, from 15 cm in the first trial to 30 cm in the second and then 50 cm in the third.Dependent: In this experiment we will measure the oxygen bubbles the plant releases into the water, per minute, to determine the rate of photosynthesis. Constant: * The species of plant (Cabomba) and the specific plant specimen is going to be kept the soma throughout the experiment because most different species or specimens may photosynthesize at a different rate to others. * The amount of water was also kept constant * The temperature of the water was kept constant at about 25 degrees Celsius (Room Temperature) as nothing was done to alter it throughout the experiment. The time periods were also kept constant as we did three trials of five minutes each and always measured the amount of bubbles per minute. Method: 1. Add Sodium Bicarbonate to the water 2. Put plant in water 3. Put the lamp at 15 cm for the beaker containing the plant specimen. Make sure this is measure accurately 4. Light the lamp at the same time as the timer is started 5. Observe, count and document how many oxygen bubbles were released by the plant Materials: 1. Water 2. Sodium Bicarbonate 3.Lamp 4. Glass Vile 5. Funnel Data Collection: Measure| 15 cm| 30 cm| 50 cm| 1| 4| 3| 4| 2| 5| 5| 2| 3| 5| 5| 2| 4| 3| 4| 3| 5| 6| 1| 4| Average | 4. 6| 3. 6| 3| Discussion: The results show, that on average, the further the lamp was moved away from the plant, the fewer bubbles formed. This is due to the fact that the lamp provides heat and light for the plant, to components that are vital for photosynthesis to occur. The bubbles in the water were oxygen bubbles that are released by the plant as it respires.As the lamp is further away the plant receives less light and therefore slows the rate of photosynthesis. With less photosynthesis the plant begins to release fewer oxygen bubbles. Evaluation: Our experiment went fairly well, however our results were not very accurate for various reasons. Firstly, the lamp we sued was a simple table lamp instead of UV light used to mimic sunlight. Therefore the light used was not an accurate imitation of sunlight. This may not have allowed the plant to increase it’s rate of photosynthesis to the fullest.Therefore the rates may have been lower then they would have been in the plant’s natural environment. The second factor that may have made our experiment less accurate was the fact that the lamp was not the only source of light hitting the plant. There was general ceil ing lighting in the room and a small extent of daylight falling on the plant. This can also have slightly manipulated our results, as we cannot be entirely sure if the rate of photosynthesis was solely influenced by the distance between the lamp and the plant and not by he other light sources in the room. We did not make any measurements of the temperature of the water or discuss the effects this may have had on the rate of photosynthesis. We also knew very little about the natural environment of the Cabomba plant. Therefore our experiment was not an accurate imitation of the plant natural process of photosynthesis, as we had to apply more components such as water temperature, proper lighting etc.We were very successful at measuring the amount of bubbles released per minute as we took turns and worked very successfully as a team, one member taking the time and the other watching and counting the bubbles, therefore we believe that our recorded results are fairly accurate. We also mad e sure that the lamp was always at the aforementioned distance from the plant specimen. Therefore I believe that our results were rather accurate given that they were recorded in a classroom environment. Conclusion: