| Explore | From experience, we know that plants need water and sunlight to grow and survive. There are many different types of plants with each having their own characteristics that help them survive. While taking AP Bio and through background research, we have learned that plants go through a process to produce oxygen, photosynthesis, and a process that produces carbon dioxide, cellular respiration. We have also learned that when a plant seed has water it could germinate with or without light, however, light must be present for a plant to continue to grow. Our group was interested in how each plant could grow and how their characteristics helped them adapt to their environment. |
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| Research Question | We wanted to test if the pH of a solution would increase/decrease with the presence of either oxygen or cellular respiration. This experiment was a continuation of our first experiment where we tested to see if plants could go through the process of photosynthesis or cellular respiration in both dark or light experiments. We came up with the question after we did our first experiment and noticed a color change in phenol red. This made us curious as to why the color changed and whether or not it affected the pH. This question fits our topic since it involved plants and the our knowledge of how we know photosynthesis occurs only in the light while cellular respiration happens in both light and dark environments. |
| Predictions | Independent Variable: Light/Dark of Environment Dependent Variable: Before/After pH of the Solution Control Groups: Same Species of Plant, Amount of Time It Was In The Environment, Amount of Plant Disc In Each Cup The possible outcomes of our study was the increase/decrease of pH. We predicted that the pH would probably increase in the light and decrease in the dark. That is due to the fact that in the light photosynthesis and cellular respiration takes place which would release oxygen and carbon dioxide into the solution. In the dark only cellular respiration would take place which releases only carbon dioxide in the solution further lowering the pH. When we measure the pH of all six solution after 24 hours, 3 of the cups in the light would have an increased pH and in the dark, it would have a decreased pH. |
| Experimental Design | We decided to use the leaves of the plant Scindapsus Jada Pothos. A member of our group punched out 36 discs from the leaves and separated it into groups of 6. Another member made a pair 3 different solutions leaving us with 6 different cups. Our first set of solution was limewater. In a cup we poured 200 mL of soap water and 5 mL of limewater. That was our first set which one was put in the light and the other in the dark. The second set was 200 mL of phenol red. 200 mL was placed in the dark and 200 mL in the light. Our last set included 200 mL of soap water and 1 mL of universal indicator, one placed in light and one in the dark. We measured the pH of each solution before setting it in their separate environments. They were in the light/dark for 24 hours in total. When we removed them the next day, we remeasured the pH to see whether it increased or decreased. We will test the pH of the solutions and we will also measure the pH after 24 hours. Secondly, we might observe the color of the solutions to see if it had changed. We will keep the time and plant species constant throughout the whole experiment and for each solution. We will record our data using charts that show the difference in pH. |
| Conclusion | From our experiment, we can make a claim that there was more carbon dioxide produced in the dark than in the light. We know that carbon dioxide is a product of cellular respiration and its counteract opposite is oxygen. Oxygen is a product of photosynthesis and photosynthesis can not happen in the dark. Due to the fact that there was only cellular respiration happening in the dark, there was no oxygen to cancel out the carbon dioxide. To further continue this experiment, we can redo this procedure again as well as just use simple water instead of the other solutions/solvents. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Michele Piatt |
| School Name | Charleroi Area Middle/High School |
| Session | Fall 2023 |
| About this Project | Good communication between the mentor and the students, and good record of the data. Students showed interest in the experiment making questions. -- Gabriela Hernandes Villani, Liaison This group really worked together to communicate with their scientist mentor at every step of the investigation. They were vary thorough in their discussions and asked intriguing questions. The design of their experiment was innovative as they used additional materials beyond the Planting Science investigations. -- Michele Piatt, Teacher |
