| Explore | From outside experiences, we knew that plants are photosynthesizers, which also made them autotrophs. We knew that for plants to get energy they need to photosynthesize using sunlight, carbon dioxide, and water. Our team also knew that plants release oxygen as a by product of photosynthesis. We discovered many other things about plants in class and through background research. We learned that plants contain pigments other than chlorophyll, there are two separate reactions that occur during photosynthesis (light independent and light dependent/Calvin Cycle reactions), and that plants absorb light with certain wavelengths better than other kinds of light. We learned that the oxygen released from plants comes from water, and that glucose that plants produce is derived from carbon dioxide that is reduced to a carbohydrate with hydrogen from water. We learned more about Wisconsin Fast Plants through background research. Wisconsin Fast Plants are a vascular plant that have about 40 day life cycle, and usually reach about 20 cm in height. They do not require a large amount of space to grow, and they require a constant flow of fluorescent light. Wisconsin Fast Plants also exhibit some traits that aren't usual for research organisms: they only reproduce sexually and they rarely self pollinate. Some questions about plants that interest us are: 1) Are there certain ways to increase the rate of photosynthesis in plants? 2) Is there a way to affect the final mass or height of a plant? |
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| Research Question | Our team wants to test whether the addition of ultraviolet light energy along with visible light will cause a group of Wisconsin Fast Plants that is exposed to it will grow taller than a group that isn't exposed to the ultraviolet. We came up with this question using a "Four Question Strategy" that our biology teacher, Mr. Roche taught us. The first question was "What materials are readily available for conducting experiments on plants ?" We made a list of materials that we had available to us to answer that question. The next question was "How do plants act?" For this question, we just listed everything we had known about a plants at the beginning of this study to answer it. The third question expanded on the first two: How can we change the set of lighting materials (fluorescent, incandescent, etc.) to affect the final height of the plants. We then narrowed the third question to decide what we wanted to test. The fourth question was "How can we measure or describe the response to the change?" While this fourth question didn't help us realize what we wanted to test, it led to us planning out HOW we wanted to setup the study. The question fits what we know about the topic because we learned that plants use light to photosynthesize, light that is not reflected by plants is absorbed by chlorophyll and other pigments in plants, and photosynthesis is how plants gain energy and material to grow with and perform structural functions. |
| Predictions | The possible outcome of our study, given what we are working with, is that the Wisconsin Fast Plants that are exposed to ultraviolet rays along with fluorescent light (imitating sunlight) will grow taller than the Wisconsin Fast Plants that are not exposed to the ultraviolet light. The reason that this will happen is because the plants in the experimental group (the ones exposed to the ultraviolet) will photosynthesize faster and have more material to grow with. This would be a direct result of being exposed to an additional type of light which will be absorbed by the chlorophyll and other pigments in the plants, which will give the chloroplasts even more energy to perform light independent reactions. |
| Experimental Design | To measure this data, we came up with an experiment to record and conclude whether our hypotheses were supported or not. There are two groups of fifteen Wisconsin Fast Plants receiving light from a fluorescent light fixture: the experimental group having a black light supplement (to provide ultraviolet rays) as well as the fluorescent and the control receiving only the fluorescent light. The whole set up is in an aquarium with a divider set up made of cardboard. The plants are planted with rock wool, with 15 blocks in a 3 x 5 array on each side. The control group is towards the inside of the counter, while the experimental group is towards the outside edge, so that the black light only shines on the experimental group. The independent variable is whether or not the plant group was receiving ultraviolet rays through a black light supplement. The dependent variable will be the average final height of the plants. This will be measured by finding the heights of all the plants in one group, finding the sum of the heights and then dividing that by the number of plants in that group, fifteen in this case. Then we will compare this to the height of the control plants and find whether the black light supplement made a significant difference or not. There is a total of thirty plants meaning fifteen plants in each group. Both groups receive fluorescent light at the same amount with the same intensity and time periods. Both groups will receive the same nutrient solution at the same time. Both groups are the same plant species, Brassica Rapa. We will measure the end data by comparing the average final height of the experimental group to the average final height of the control group. This data will be represented through a bar graph as well as a table depicting the individual plant heights of both control and experimental groups. |
| Conclusion | Based on our experiment we can make the claim that the use of a UV light supplement does not cause Wisconsin Fast Plants to grow taller. There are a few possible explanations for our results: 1) since Fast Plants are traditionally grown under fluorescent lights, the use of a UV light supplement did not make a difference in the rate of photosynthesis in the experimental group and 2) the UV light was not shining at an intensity high enough to affect the rate of photosynthesis. |
| Investigation Theme | WOS |
| Grade Level | High School Students (Grades 9,10,11,12) |
| School Name | High Technology High School |
| Session | Fall 2016 |
