Turn That Light Up: Examining the Effect of Light Intensity on Photosynthesis as Measured by Oxygen Production in Elodea canadensis

Abstract

Photosynthesis is an essential reaction occurring in all plants as it provides their source of energy. As light is one of the required reactants, we chose to investigate the effects of differing light intensities on the rate of photosynthesis, hypothesizing that greater light intensity will result in greater photosynthetic rate. The rate was measured by determining the change in oxygen concentration in the medium by the aquatic plant, Elodea canadensis. The plant was immersed in the medium and subjected to different light intensities over three independent trials. Although we were unable to find any statistical differences between change in oxygen concentration and the light intensity, a slight trend suggested light intensity did have an effect on the rate of photosynthesis. The effect of light intensity followed a Michealis-Menten curve where increases in light intensity corresponded to increases in oxygen production until a peak in oxygen production occurred at a light intensity of 6000 lux. From this, we suspect that E. canadensis has an optimal photosynthetic rate at light intensities of 6000 lux. At greater intensities oxygen inhibition begins to occur due to the ability of the enzyme ribulose phosphatase to act in both photosynthesis and cellular respiration. However, as our results were not statistically significant, further studies would have to be performed to determine the effect of light intensity on photosynthesis in E. canadensis.