| Explore | Photosynthesis is a process through which plants absorb sunlight, triggering a reaction that creates energy plants can use. It does this by converting CO2 to O2, using the carbon to create ATP. Questions: How do plant seeds know to grow in the correct direction? What are some things that cause a tree to die when it is getting the correct amounts of sunlight and water? |
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| Research Question | Will wood smoke affect the process of photosynthesis? We thought this was a great way to determine how forest fires could harm forest ecosystems. In addition to this, smog and pollutants could similarly block out light, reducing the rate of photosynthesis, and therefore reducing the rate of plant growth. We know that light is necessary for photosynthesis, and smoke blocks light, so we wanted to determine if smoke inhibits photosynthesis. |
| Predictions | If the plant is placed in a smoky environment, then photosynthesis will be inhibited. This is because smoke will block some of the light, reducing the rate of photosynthesis. |
| Experimental Design | 1. Cut out 20 spinach disks 2. Fill two cups with 4cm of water, 2-4 drops of soap solution 3. Remove air from spinach disks by placing 10 into a syringe, and fill with 7 mL of water, pushing out excess air. Create a vacuum until all of the spinach disks sink to the bottom 4. Pour the spinach disks from one syringe into one cup, and repeat with the others. Add 1/8 tsp of baking soda to each cup. 5. Place torn-up paper towels and grill pellets in a glass dish and start the fire 6. Place one cup of spinach disks under a light with fire and cover with fish tank, place the other under the other light. Wait for there to be a good amount of smoke to turn on the lights. 7. Turn on both lights at the same time, and start a stopwatch 8. Record the amount of disks floating in each cup every minute until all of the disks are floating in both cups (may repeat with less smoke) |
| Conclusion | Smoke inhibits the rate of photosynthesis. Light is necessary for photosynthesis to occur. When light hits the chlorophyll, it changes H20 into 02 gas. The smoke is preventing the light from reaching the chlorophyll, so 02 production decreases indicating that photosynthesis is also inhibited by the smoke. Someone could do a long-term experiment, exposing plants to smoke for a long time, determining the long-term effects of smoke on photosynthesis. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Theresa Ellefson |
| School Name | Osceola High School |
| Session | Fall 2023 |
| About this Project | The members of this team came up with a very cool research question about how smoke affects plants' ability to photosynthesize. While this isn't a novel question, it showed to me that they were thinking about things that have real world consequences and something they were deeply interested in. We have had consistent communication from design to implementation of their experiment and it was clear that they had thought about their questions for me and took the advice that I provided to them. They also have done an excellent job of communicating their results and what they think they mean to me. They're on their way to being effective scientists if that is what they choose to pursue in the future and I believe that positive recognition for their work is deserving as well as uplifting. -- Jennifer Riehl, Mentor |
