Biology Lab: Student Projects – Abstract
Maia S. Rowland
Shaina M. Stein
Ann L. West
For this experiment, we chose to study the rate of photosynthesis of the Juniper plant when subjected under both red and blue light. In a previous study, we found that more light energy is absorbed under blue/violet causing the rate of photosynthesis in that plant to be faster. Based on the information from this previous study we were able to make our hypothesis. If the blue light is shining on the Juniper plant it will have a higher rate of photosynthesis because the blue light has a higher amount of energy. In order test our hypothesis; we first measured and put 14.15 g of Juniper, each, into three different clear, plastic containers. We then subjected the plant to red light for ten minutes with a CO2 sensor inserted into the top of the container holding the Juniper to graph its levels. We then repeated the procedure with the two other containers but with one subjected to blue light, and the final one subjected to no light. We were able to make the container completely dark by wrapping the final container cautiously with foil. After each container had been subjected to the certain color light and/or no light at all, we were able to examine our results. Unfortunately, there was not enough data in our experiment to reject, approve, or modify our hypothesis due to the fact that a reliable t-test could not be preformed. However, disregarding the t-test and solely basing our results on the mathematics done to figure out the rate of photosynthesis for each color, it is likely that plants subjected to blue light would have a greater rate of photosynthesis. We were able to conclude this because under blue light the rate was the most negative of the two implying that the most CO2 was being absorbed into the plant for photosynthesis to occur. In using this as a probable conclusion, we are able to state that our results were consistent with our hypothesis. Nevertheless, there are many potential problems in performing our experiment. It is very likely that we could have had a faulty CO2 gas senor giving us incorrect readings throughout the experiment. We also only preformed this experiment once through meaning it is not entirely reliable as well as we might not have left the plants subjected to the light long enough for true photosynthesis to begin. The importance of replication is to duplicate your experiment many times to insure its results are accurate, if only completed once the results could be slightly off or even drastically incorrect. With doing the experiment more then once the likelihood of it being incorrect is lowered. Lastly, we also could have had possible light leak into our dark portion of the experiment causing faulty mathematics when finding the rate of photosynthesis. Our hypothesis can further be analyzed by examining the results of the articles written by K. Luning (et al.) and Young-Whan Choi (et al.). In the article Reproduction, Growth and Photosynthesis of Gametophytes of Laminaria saccharina Grown in Blue and Red Light (Luning et al. 1975) the scientists were able to prove that the Gametophytes became more fertile in blue light, however they cannot fully accept that blue has a more profound effect on growth. They were left with the plants grew at similar rates in both red and blue light. In the next article I examined, Growth, photomorphogenesis, and photosynthesis of perilla grown under red, blue light emitting diodes and light intensities, (Choi et al. 2003) the authors concluded blue LEDs lights resulted in a lower photosynthetic rate than those grown in red LEDs light (Choi et al. 2003). This was shown because “there were fewer leaf numbers and leaf area under blue LEDs than those of red LEDs and MH lamps.” However, the stems of the blue LEDS were clearly taller but had thinner stems. Both articles do not necessarily verify our possible hypothesis but they do provide us with more information concerning our results.
Lüning, K. & Dring M.J. 1975. Reproduction, Growth and Photosynthesis of Gametophytes of Laminaria saccharina Grown in Blue and Red Light. Marine Biology 29: 95-200.
Choi, Young-Whan et al. 2003. Growth, photomorphogenesis, and photosynthesis of perilla grown under red, blue light emitting diodes and light intensities. Journal of the Korean Society for Horticultural Science. Vol. 44 (3). 281-286