| Explore | We’ve already tested the rate of photosynthesis of spinach disks with variables such as pH and presence of light. We discovered that plants photosynthesize faster in an acidic solution for the pH factor. Plants will photosynthesize only when exposed to light rather than no light for the presence of light factor. We’d like to explore the idea of the differences between C3 plants and C4 plants involving their rates of photosynthesis. The C3 plant we would like to test is mint and the C4 plants we would like to test is a succulent. |
|---|---|
| Research Question | The question we would like to test is how does type of plant, C3 (mint) or C4 plant (succulent) differ in terms of the rate of photosynthesis? We came up with this question because we have some knowledge about how C3 plants photosynthesize as we did experiments involving spinach disks, but we do not have significant knowledge about C4 plants. This experiment can provide us with some knowledge about C4 plants. We will testing the rate of photosynthesis, a topic we already know a lot about from class and other experiments, we can already draw conclusions on what the C3 plant results will yield. |
| Predictions | Rate of photosynthesis will differ between C3 and C4 plants. Depending on the temperature, one (possibly C4 may not photosynthesize at all. Rate of photosynthesis will be faster for the C3 plant than the C4 plant due to the fact photosynthesis is occurring at room temperature, a suitable environment for C3 plants. C4 plants thrive in hotter temperatures not at room temperature, so photosynthesis will occur slower. CO2 levels will drop and O2 levels will rise. |
| Experimental Design | Dependent Variable: Rate of photosynthesis in C3 and C4 plants over period of time (at room temperature) Independent Variable: Type of plant being tested (C3 or C4) Control Variable: Rate of photosynthesis of each plant without any light Experimental Condition: Same amount of light for each plant, same temperature (room temperature), same soil and the same environment of testing ( Biochamber is a controlled and regulated environment) Hypothesis: The C3 plant will photosynthesize at a faster rate than the c4 plant in a room temperature environment. The C3 plant undergoes cellular respiration at a faster rate because the C4 plant has evolved to photosynthesize in a much harsher environment compared to a C3 plant, so when it is out of it’s typical environment it won’t photosynthesize like it usually does. |
| Conclusion | Looking at our results, we can see that C4 plants are better at photosynthesizing at room temperature (22-23 degrees Celsius). Based on the graphs, the C3 plant had high CO2 levels and they were continuing to rise. While this was happening the oxygen in the chamber was dropping, showing that cellular respiration was happening faster than photosynthesis in C3 plants at room temperature. The C4 plant surprised us because in the beginning both the oxygen and CO2 levels were high, but after about 5-10 minutes the CO2 dropped and remained low, while oxygen levels increased. This shows that the C4 plant photosynthesizes at a faster rate than cellular respiration happens. To understand why the C4 plant photosynthesized faster than the C3 plant at room temperature, we may have not considered that the lamps we used to initiate photosynthesis could have given off some excess heat, bringing up the temperature in the biochamber 2000 from our moderate room temperature. |
| Investigation Theme | POS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| School Name | David & Mary Thomson C. I. |
| Session | Fall 2017 |