1. Mrs. Winstead’s Adv Biology class Waterloo West High School 2012-2013 The Effects of Water Temperature on the Rate of Photosynthesis in Spinacia oleracea Photosynthesis is the process that plants go through when converting light energy to chemical energy and storing it as sugars. Photosynthesis requires light energy, CO2, and H2O. It takes place in the chloroplasts. The equation for photosynthesis is 6CO2 + 6H2O (+ light energy) -> C6H12O6 + 6O2. Within the plant cells of leaves, there are chloroplasts. Within these chloroplasts are thylakoids. And within the membranes of these thylakoids are electron transport chains to convert light energy into sugars. Light energy hits photosystem I of the electron transport chain, exciting the electrons. The electrons then travel down the electron transport chain and bind to NADP +. Two hydrogen molecules also bind to NADP+, forming NADPH. As the electrons move down the electron transport chain, hydrogen will move across the membrane into the thylakoid space. This makes for a greater concentration of hydrogen molecules in the thylakoid space, and they move through the ATP synthase to form ATP, a process known as chemiosmosis. Two oxygen atoms combine to make O 2 gas, and the photosynthesis is complete. We used the leaf flotation method to measure the rate of photosynthesis. Once the oxygen is removed from each portion of a spinach leaf, they sink to the bottom of a glass beaker filled with carbonated water. When the beaker with sunken leaves is placed beneath a fluorescent light bulb, more oxygen is created and fills the spaces in the leaves as photosynthesis occurs, bringing them to the surface. The time that it takes for each leaf portion to rise is measured and is analyzed as the time that it takes for the spinach to photosynthesize in the given conditions. Our purpose in this experiment was to prove our hypothesis that, “If the temperature of carbonated water is increased, then the rate of the photosynthesis will increase as well.” Methods & Materials “Photosynthesis.” Photosynthesis. SciLinks, 1996. Web. 13 Mar. 2013. Rachel Michaela Maggie Lynlee Introduction Results Discussion References Our original question was “Will the temperature of CO 2 water affect the rate of photosynthesis in discs of spinach leaves”. Our results relate to our question by the amount of time that the spinach discs took to all raise to the top. The ones in the warmer water rose to the top much faster than the ones in the cold water. The data that we received supported our hypothesis that stated that the leaf discs in the warmer water would be able to photosynthesize more rapidly than the ones in the colder water. Some of the results that we received were a little bit awkward because out of the three trials done with each temperature of water, there was always one that ended up having slightly longer times. Maybe it was because of the spinach leaf, or maybe it was just because the temperatures were slightly different. We did make a few mistakes that could invalidate our data. When we had placed the discs in the syringe and filled it with water, some of the water was room temperature, and others had reached temperature. We aren’t sure if this had a significant effect on our results, but the possibility remains. To answer questions concerning why the leaf discs take longer to raise in the same temperature water, we would need to conduct more than three trials for each temperature. 1 2 3 4 5 During our experiment, we collected data to study the question, “How does the temperature of carbonated water affect the rate of photosynthesis. The warmer trials obviously were the most successful, as they took the least amount of time to rise. Our conclusion based on this analysis is that if plants receive warmer water, then they will photosynthesize more quickly.The reason for this may be that warmer substances have particles that move at greater speeds, and that could, in turn, speed up the process. Because we don’t have the complete data for the cold trials, the graph plummets to zero minutes. In reality, it is because the discs took longer than 20 minutes, which was our cutoff, to rise to the surface. The data table shows these incomplete times as zeros as well. Put Your Logo Here To replicate this experiment, you’ll need the following materials: -Needleless syringes -Spinach leaves -A hot plate -An electronic balance -Glass beakers -Plastic cups -A hole punch -Baking soda -100 watt fluorescent light bulbs -2 ? Quart tubs -Empty glass dishes 1.Weigh one of the plastic cups and zero out the balance, then add baking soda until you have a total of 1 gram. 2.Add the baking soda to 100 milliliters of water. Repeat until you have 3 water samples 3.Heat one sample to 38˚ Celsius (~100˚ Fahrenheit), chill one to 5˚ Celsius (~40˚ Fahrenheit) and keep one at room temperature (~20˚ Celsius, 70˚ Fahrenheit) 4.While waiting for the samples to reach temperature, punch out 10 discs from spinach leaves using the hole punch. 5.Remove the plungers from the syringes and place 10 discs in each one. Replace the plungers without crushing them. 6.Add 12-15 mL into the syringe, get rid of the excess air, and cover the end with your thumb. Pull back to create a vacuum, and shake. Continue until the discs settle along the bottom. 7. Place the deoxidized discs in a room temperature sample and place the beaker under the light bulb held by the plastic tub. 8. Time how long it takes for each of the ten discs to rise. 9. Repeat this trial three times. 10. Repeat steps 1-9 for the other temperatures. 11. Record the data in a table. 12. Average the times for each disc in each trial for the different temperatures. Figure 2: A graph of our final averaged times for each temperature. Figure 3: The data table that shows the exact averaged times for each temperature we chose. 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