Photosynthesis Lab Report

The purpose of this experiment was to see what the effects of light and dark would have on photosynthesis and cellular respiration. With the knowledge gained in class about how both the reactions took place. It was predicted that the absence of light would slow down photosynthesis causing less O2 to be released in the water. It was also predicted that the beaker with the fish in the water would yield a higher concentration of CO2 in the water. These predictions were made based on the fact that plants use the energy from light in photosynthesis to split H2O creating an oxygen by product. Also cellular respiration is an aerobic reaction meaning it require oxygen to take place and releases a CO2 by product. In the experiment aged water was used as the control. The CO2 and O2 levels were tested and used as the base level coming in at 7.6ppm for O2 in Table 1 and 12.3 ppm for CO2 in Table 2. Three variables were set up with controls. First was a fish in a beaker filled with aged water with an additional beaker of aged water for the control. Then a beaker with elodea leaf in aged water was placed in direct light with a beaker of aged water also placed in direct light for control. Last a beaker with elodea leaf in aged water was placed in the dark with a beaker of aged water also placed in the dark for

The beaker containing the fish and aged water for 1 hour showed a CO2 level of 21.5 ppm up from 12.3 ppm in the control beaker of aged water correlating with the stated predictions. Also in Table 1 the beaker containing elodea leaf placed in the dark for 1 hour showed O2 levels of 7.2 ppm about the same as the control aged water at a level of 7.6 ppm. Although the prediction was photosynthesis would slow down releasing less O2 than the elodea leaf in aged water placed in light. It seemed to halt photosynthesis all together not releasing any extra