Photosynthesis is the process of converting solar energy, carbon dioxide (CO2), and water (H2O) into carbohydrates (CH2O) and oxygen (O2). Sometimes the end product of photosynthesis is glucose (C6H12O6). Photosynthesis takes place in the chloroplasts of plant cells. Here membranous thylakoids are stacked in grana surrounded by the stroma. During the light reactions, pigments within the thylakoid membranes absorb solar energy, water is split, and oxygen is released. (Mader, 2010) In this study, we are interested in examining the effects of photosynthesis in spinach leaves in the presence of different light conditions. The light conditions that will be tested are no light, white light and green light. Therefore, we hypothesized that the O2 rate of consumption would occur more in the green light condition and CO2 rate of consumption would occur more in the no light condition. Methods
A laptop computer with Logger Pro Computer Program connected to a Vernier LabQuest Computer Interface. A Vernier O2 Gas Sensor and a Vernier CO2 Gas sensor connected to the Vernier LabQuest Computer Interface are used to measure the amount of oxygen and carbon dioxide produced. The spinach leaves are placed in the 2000 mL respiration chamber. A 150 Watt goose neck lamp is used as the primary light source. Aluminum foil is wrapped around the 2000 mL respiration chamber is used to test the no light condition. The 500 mL Beaker is filled with water and placed in between the respiration chamber and the goose neck lamp. The instructions on the photosynthesis lab handout were used to carry out the experiment with the following change. Green food coloring was added to the 500 mL Beaker to test the effects of photosynthesis in green light. Results
After collecting data for 15 minutes for spinach leaves in each light condition, we found that the rate of CO2 consumption for the spinach leaves were higher in the no light condition than any of the other light condition with the spinach leaves (Table 1). We also found that the rate of O2 consumption was higher for the spinach leaves in the green light condition. The no light condition, light condition, and green light condition had CO2 rates of 1.543, -1.922, and -0.0002375 respectively. The O2 rates of consumption for the no light condition, light condition, and green light condition were 2.51, 2.55, and 2.63 in that order.
Leaves| CO2 rate of production/consumption (m=Slope)| O2 rate of production/consumption (m=Slope)| In no Light| 1.543| 2.51|
In the Light| -1.922| 2.55|
In the Green Light| -0.0002375| 2.63|
We collected data for the CO2 and O2 consumption rates of spinach leaves in a no light condition, a light condition, and a green light condition. The spinach leaves in the no light condition had a higher rate of CO2 consumption than both the light condition and the green light condition. The spinach leaves in the green light condition had a higher rate of O2 consumption than both the no light condition and the light condition. We can accept our hypothesis that the CO2 rate of consumption would be higher in the no light condition because the no light condition had a significantly higher rate of CO2 consumption than the other two light conditions. We can also accept our hypothesis the O2 rate of consumption would be higher in the green light condition because the green light condition had a much higher rate of O2 rate of consumption than the other two light conditions. References Cited
Mader, Sylvia S. (2010). Georgia Perimeter College Biology 1402: Select Labs From Laboratory Manual to accompany Biology, Tenth Edition. Burr Ridge, IL: The McGraw-Hill Companies, Inc.