| Explore | Photosynthesis can only happen when light, CO2, and water is present. As long as those three components are present, photosynthesis can occur just about anywhere. These past experiments have shown that photosynthesis is affected by light and CO2, which is what this experiment is testing. The more CO2 and the more light, the faster photosynthesis happens. This investigation was formulated based on the question, “How do different amounts of light or CO2 affect photosynthesis in a plant?”. This investigation was something that intrigued each group member. It required higher level thinking and was something different than previous experiments. |
|---|---|
| Research Question | This experiment will test how different amounts of CO2 affects photosynthesis. In the first experiment, there were three cups, each one with a different type/amount of CO2. The first cup had only water in it, the second had breath and water, and the third cup had a baking soda and water solution. In this experiment, it is a little different. The experiment will use different amounts of CO2, but instead of different ways of getting it, it is only baking soda. There are 4 cups, one with just water, one with a half a teaspoon of baking soda, one with 2 teaspoons, and one with the baking soda solution that has been previously used. Each cup will be exposed to the same amount of light and use the same amount of water. |
| Predictions | If the cup of water has more baking soda (CO2), then that cup will have more floating spinach leaf disks. This is supported by the previous experiment where the cup with the baking soda solution had the most floating spinach leaf disks. It was determined to have had the most CO2 and that is what caused the spinach leaf disks to float. |
| Experimental Design | There will be three separate cups with baking soda solution in them. Cup one will have a half a teaspoon of baking soda in the solution, Cup two will have the normal baking soda solution from past experiments, and Cup three will have two teaspoons of baking soda in the solution. Ten leaf disks for each up are cut from spinach leaves (the same way created for past experiments) and placed under the same light. The amount of floating leaf disks, and non-floating leaf disks, is recorded over a seven minute time period. The independent variable for this experiment is the amount of baking soda in the cup. The dependent variable in this experiment is the floating spinach leaf disks. For this experiment the control group is the normal water. Experimental group consists of the amounts of baking soda per cup. Lastly the constants are the cups, spinach leaf, light source, and syringe. Keeping the same type of leaf is key because it is unknown what would happen if different plants are used. A different light source for each cup may affect the results for the experiment. |
| Conclusion | From our experiment, the claim that the more CO2 there is, the faster photosynthesis will happen is supported . The data collected shows that the solutions that had the most CO2 produced the most floating disks, whereas the solutions that had the least amount of CO2 didn’t produce as many floating disks in general. The data supports our claim that if there is less CO2, then there will be fewer floating leaf disks. The data shows a total of how many final disks were floating. There were less floating disks in the solutions with less CO2, compared to the solutions with the most CO2. For example, the solution with just a half a teaspoon of baking soda only produced one floater over the course of the entire experiment. Whereas, the solution with 2 teaspoons of baking soda, produced a total of 6 floaters over the course of the whole experiment. But, although more CO2 promotes the process, it can also prohibit it. During our experiment, the cup with the most CO2 had a total of 6 disks floating, compared to the average baking soda solution producing 10. So, we came to the conclusion that if there isn’t enough CO2, or there is too much CO2, it can take a toll on the life of a plant, and the way it performs photosynthesis. In the cup with the two teaspoons of baking soda, it was discovered that there was too much baking soda, causing the leaf disks to get stuck. This issue was solved by adding more water to further dilute the baking soda in the cup. In the future, this experiment could be performed and would have the same format but on a larger scale, and a larger amount of time for the experiment to be conducted. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Sarah Tschauder |
| School Name | Atchison High School |
| Session | Fall 2023 |