Planting Science - Projects: Group 1
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Group 1

Project by group sjalodesfall2018

Explore Photosynthesis is the process in which plants convert light energy into chemical energy using water and carbon dioxide. It was discovered by Jan Baptist von Helmont, a Belgian scientist, that water is required for photosynthesis to be carried out in his exploration of where plant mass comes from, in which he concluded that an increase in plant mass was due to the watering of the plant. In addition to water, Joseph Priestley concluded that oxygen is given off as a byproduct of photosynthesis in his experiment that placed a living organism inside of an enclosed environment with a plant. Covered by the glass enclosure without the photosynthesizing plant, the mouse suffocated. It was found out by scientist Jan Ingenhousz that sunlight is necessary in providing energy to catalyze the reaction of photosynthesis through his experiment of placing leaves under water and covering them with a test tube that would capture the oxygen gas bubbling from the leaves. He placed one group in light and another in the dark; the one in the dark did not produce oxygen, therefore, it did not photosynthesize. The products of photosynthesis are oxygen gas and the sugar glucose, which is an important source of energy broken down to produce adenosine triphosphate (ATP) molecules. Although water, carbon dioxide gas, and sunlight are necessary components of photosynthesis, the temperature at which a plant is exposed also contributes to how efficient the plant is at photosynthesizing. For example, regions with extreme weather, like deserts or tundras, yield low amounts of plant species diversity due to plants’ inability to withstand severe temperatures. Also, all enzymes needed in photosynthesis are temperature sensitive.
Research Question The purpose of this lab was to study the process of photosynthesis and the effect of temperature on the rate of photosynthesis, specifically if an increased temperature increases the rate of photosynthesis. The factors affecting photosynthesis, such as the presence of carbon dioxide, light, and water, were also studied. Studying the effects of increased temperature on plant photosynthesis is relevant in understanding the effects of global warming in various regions.
Predictions Hypothesis: If the temperature of the water is increased, then the number of spinach disks that will rise to the top (undergo photosynthesis) will increase. This is predicted because of prior knowledge relating to metabolic processes. And in the winter and fall trees lose their leaves and become dormant during the winter.
Experimental Design Procedure: 1. Used caution when working with materials (Used safety equipment when necessary) 2. Poured approx. 600 mL water into large beaker 3. Added approx. 12 grams of baking soda into water 4. Stirred until completely dissolved 5. Added baking soda and water mixture into 3 plastic cups 6. Placed one cup into ice bath 7. Placed one cup into heat bath 8. Left one cup out (room temperature) 9. Added distilled water to plastic cup (control) 10. Measured temperature of water (cold=13 degrees Celsius; hot 42 degrees Celsius; room temperature= 20 degrees Celsius) 11. Cut out 80 leaf disks 12. Separated into 4 groups of 20 13. Placed into syringes 14. Sucked water into each syringe (Used distilled water for control) (Used remaining baking soda solution for manipulated trials) 15. Removed oxygen from spinach disks (created and removed pressure in syringe) (Did this process until all disks fell to bottom of syringe) 16. Added spinach disks into correlating trail and control cups 17. Made sure all disks started on the bottom of the cup 18. Started time (once all disks were in cups) 19. Recorded number of disks that rose to the surface of the water every minute for 25 minutes 20. Recorded all information into data table 21. Cleaned up and put away materials Variables: The independent variable in this experiment is the temperature of the water, in degrees Celsius, in which the spinach disks are in. This variable will be measured using a thermometer and will be controlled using an ice bath and a heat bath. The dependent variable in this experiment is the number of spinach disks that rise to the top of the water (observation of photosynthesis occurrence). This variable will be measured by counting the number of disks that have risen to the top of the water every minute for 25 minutes total. The constant variable in this solution include the type of spinach, the amount of baking soda in the water solution, the location of conducting the trials, the plastic cups used, the size of the spinach disks, they way oxygen was compressed out of the spinach disks. The control group in this experiment was spinach disks in distilled water (no baking soda) in room temperature water. This was the control as the rest of the solutions had baking soda added to the water solution which adds carbon dioxide to the water which is necessary for photosynthesis to occur.
Conclusion Conclusion: The purpose of this lab was to study how the rate of the process of photosynthesis is affected by temperature on the rate of photosynthesis. In particular, the purpose was to test if an increased temperature increases the rate of photosynthesis. The initial hypothesis was that higher temperatures would cause the rate of photosynthesis to increase, and the results of the experiment support this hypothesis. In the cold water, after 25 minutes, 2 leaf disks rose to the top. For the room temperature, 17 were at the top. And for the cold water, 2 disks rose to the top of the baking soda solution. According to the data collected, and as seen on the graph, the leaf discs submerged in hot water rose to the top at a much faster rate than the discs in cold water. There were many possible sources of error present in this experiment. After removing the oxygen from the leaf discs using syringes, the groups of leaf discs were mixed up, and it became unclear which syringe contained the discs for the control variation. Therefore, it is possible there was a small amount of baking soda present in the control, which was supposed to contain only distilled water. This error could have been avoided by keeping the syringes separate or labeling them so they don’t all look the same. Another possible source of error would be miscounting how many discs rose to the top within certain periods of time. It is possible the cups may have ended up with fewer than or more than twenty leaf discs, so the resulting data would have been incorrect. Recounting could have been used to avoid this error. An additional source of error occured when labeling the room temperature cups for distilled and baking soda solution. With results from prior experiments this lead it to be believed that the cup labeled distilled water was actually baking soda and the cup labeled baking soda. This inferred switch was an error and it could have been avoided by being more attentive to which cup was which when placing labels. Finally, another source of error could have been that certain cups had better access to light that others. Two lamps were used to provide light for all four cups, so some were closer to the light that others. This error could have been avoided by placing the cups under grow lights, or even using one lamp per cup in order to provide each variation with the exact same amount of light. From this experiment it was learned that higher water temperatures cause an increase in the rate of photosynthesis. Studying the effects of increased temperature on plant photosynthesis is important because it can provide an understanding the effects of global warming in various regions. Based on this experiment, there are many other variations that could be tested. Using the spinach leaf discs, things like amount of light or different colors of light could be tested. A question that could be further explored is how the leaf discs are affected by being submerged in different water-based solutions.
Investigation Theme POS
Grade Level High School Students (Grades 9,10,11,12)
School Name St. Joseph's Academy
Session Fall 2018

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NSF_Logo.jpg This material is based upon work supported by the National Science Foundation under Grant #2010556 and #1502892. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

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