| Explore | What we know: Photosynthesis occurs when there is an adequate supply of CO2 and sunlight, which is absorbed by the photosynthetic pigment chlorophyll inside the thylakoids of the chloroplasts; and cellular respiration happens in the mitochondria most prominently during the night; photosynthesis uses temperature sensitive enzymes that slow down in cold environments, and speed up in warm environments until they overheat and denature. During photosynthesis, CO2, H20 and sunlight (energy) are taken in by the plant, and O2 and glucose are created. During plant respiration, O2 and glucose are taken in by the plant, and C02, H20, and ATP (energy) are created. Questions that interest us: do different colors of light affect photosynthesis? Does sound impact the rate of photosynthesis? What is the optimal temperature for photosynthesis for a variety of plants? How does temperature affect the rate of photosynthesis? |
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| Research Question | If one plant was placed in a constant cold temperature, one was placed at a constant room temperature, and one was moved between cold and room temperature, how would their photosynthesis production (pH) compare? Climate change and natural temperature fluctuation (especially in the Midwest United States) inspired us to test what effect that rapid temperature fluctuation has on the plant. |
| Predictions | We predict that beads that remain in the fridge will have the lowest pH, meaning that they perform photosynthesis at the slowest rate. If the pH becomes too acidic, the photosynthetic enzymes within the algae beads could denature, rendering them incapable of performing photosynthesis. The beads that remain at room temperature will have the highest pH, meaning that they perform photosynthesis at the fastest rate. Finally, the beads that are moved from room temperature to cold temperature will have a pH level in between, meaning that they perform photosynthesis at an average rate. |
| Experimental Design | We will compare 3 cubettes, each with 10 algae beads and CO2 indicators at different temperatures. One of our control groups will be at a constant room temperature (26 degrees Celsius), one will be at a constant cold temperature (kept in a refrigerator at 7 degrees Celsius), and our independent variable group will switch between the two environments approximately at the hour, throughout the school day. With the algae beads and CO2 indicator, we will measure the pH and thus the rate of photosynthesis for each cubette. We will record our data on tables initially and transfer it into a graph. Independent Variable: temperature of the environments Dependent Variable: pH (rate of photosynthesis) of the cubette switched between the warm and cold environments Control Variable (to limit confounding factors): The light was 8-inches from each cubette. We shook each stable cubette of algae beads to imitate that movement of the switching cubette. |
| Conclusion | This experiment demonstrated that a plant regularly switching between cold and room temperature environments photosynthesizes at a slightly slower rate than a plant left stationary in a room temperature environment and significantly faster than a plant left stationary in a cold environment. The reason for this is because the enzymes that catalyze photosynthesis react slower in colder temperatures. This can be seen most clearly in the data collected on day 2 where the warm cubette had plateaued at a pH of 9.1 by 11:41 am, but the switched cubette didn't plateau at a pH of 9.1 until 12:21 am. On the same day, the cold cubette never made it past a pH level of 8.7. This could explain why all plants don't instantly die during periods of changing seasons. Plants have different ways to be resilient to the cold, which is why summer plants can still be seen in the early weeks of fall and plants that grow in the fall can still be seen in the early weeks of the winter (so on and so forth). This also means that plants have some built up resilience to climate change, which can often cause rapid temperature fluctuation in traditionally temperate regions. In the future we could use a larger sample size of algae beads in more diverse temperatures to expand our experiment. When we performed the experiment this time we were only able to simulate a temperate day and a cold day, but in future experiments we could switch one cubette between a temperate and hot environment and another between a hot and cold environment to have a greater range of temperatures tested. We could also leave the switched cubette in each environment for different spans of time to see if the amount of time spent in each environment makes a difference in the data. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| Teacher Name | Jennifer Sunderman Broo |
| School Name | Mariemont High School |
| Session | Fall 2023 |
| About this Project | This project deserves consideration for a Star Project award due to the exceptional dedication and effort demonstrated by the group. Their commitment extended beyond regular class hours, with early morning and throughout-the-day involvement in meticulously switching their algae beads between various temperatures. The project's unique focus on the concept of whiplash weather, a consequence of climate change, showcases innovative thinking. I like that this group wanted to conduct research that attempted to address the impact of changing climates on plant growth and crop yield, aligning with a critical and globally relevant issue—climate change. -- Jennifer Broo, Teacher |
