Experiment: Photosynthesis Consumes Carbon Dioxide and Produces Oxygen - Lab Report Example

The pigments of leaves tend to absorb wavelengths of light from 400-700nm which is known as the optimum wavelength of the visible light spectrum for photosynthesis. On the other hand, respiration is the process by which the breakdown of sugars for energy takes place in an organism (Kalman, 2005). It takes place in the mitochondria and the by-products are CO2, H2O and energy. Both cellular respiration and photosynthesis relates in that the by-products of each process is a raw material for the other process.

In the photosynthesis experiment, five 50ml test tubes were labelled 1, 2, 3, 4 and 5 using a wax pencil. A piece of Elodea plant was placed in tubes 1-4 while except 5. Tubes were filled to the brim with 7.0 pH phenol red solution and then each tube was plugged with a rubber stopper. The surfaces of the tubes were wiped with a paper towel.

Tube 2 was then wrapped using two sheets of cellophane, tube 3 was wrapped using 2 sheets of green cellophane while tube 4 was wrapped with one sheet of aluminium foil and tubes 1 and 5 were not wrapped. The tubes were placed under bright white light for 11/2 hours and colour changes were noted in each tube. In the respiration experiment, goldfish were placed in a 50ml tube containing water with normal conditions for fish. The temperature of the water was measured and the number of breaths of the fish per 60sec recorded.

Tap water was poured into a 600ml beaker and the tube with the fish was transferred into the beaker. Small pieces of ice were added one by one to the beaker until the temperature dropped to 100C then the process stopped and several breaths were recorded. More ice was added until the temperature dropped to 50C then cold water was changed and the procedure above was repeated for the temperature of 210C and 250C. Results Table 1: change in colour of phenol red due to photosynthesis test tube solution colour at 0minSolution colour at 90minSolution colour after 1 week1 (white light)OrangeYellowOrange2 (red light)OrangeOrangeorange3 (green light)OrangeOrangeyellow4 (no light)OrangeOrangeOrange 5 (control)Orange Yellow OrangeTable 2: Number of breaths Temperature(0C)Group1Group2 Group3Average 25652014576.

67 21552610461.67 15(room)851911472.67 9801315683 577512970.33Discussion The colour of the phenol red turned to orange in all the tubes since the CO2 was absorbed from the environment within the enclosed tubes to react with water thus forming weak acid of pH around neutral hence the orange colour. But since tube 1 had all the factors responsible for photosynthesis thus Elodea took in CO2 within the tube to carry out photosynthesis thereafter lack of CO2 in water resulted in phenol red reacting and changing colour to yellow.

The other tubes except tube 5 which is a control experiment lacked visible light hence the pH remained at around neutral. The breathing rate is high at room temperature which is the optimal temperature for respiration and as the temperature falls further, the breathing rate reduces since the enzymes become inactivated. the conclusion is learnt that photosynthesis is affected by light and the by-product is O2 and consumes CO2 while respiration is affected by temperature and its by-products are CO2 and water.

While in the respiration experiment as the temperature goes down, the enzymes get denatured and therefore lose their efficiency resulting in a low number of breaths per 60 seconds.