This tutorial introduces photosynthesis

In this experiment, the effects of temperature on rate of photosynthesis in gymnosperms and angiosperms was studied through the use of some samples of gymnosperms and angiosperms, a Carbon Dioxide gas sensor, a computer, some lights and some ice. From the experiment, it was determined that colder temperatures (a colder environment) results in significantly higher rates of photosynthesis in gymnosperms than in angiosperms. Since gymnosperm needles remain green and attached to their tree branches in the winter time while angiosperm leaves turn brown, die and fall off of the branches, it was hypothesized that gymnosperms exhibit significantly higher rates of photosynthesis in colder climates than do angiosperms.

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Other sections include animal systems, cells, vertebrates, and invertebrates.

Photosynthesis Educational Videos | WatchKnowLearn

The results of the experiment indicated that the mean rates of photosynthesis for the angiosperm and gymnosperm in a warm climate, which were -1.72 ppm/min/g and -8.358 ppm/min/g, respectively, were significantly different with a p-value of 0.5811. This p-value is important, because if the gymnosperm rate of photosynthesis was significantly higher in the warm climate than the angiosperm (or vice versa), there would really be no basis for comparison, since the gymnosperm/angiosperm was higher to begin with. In support of the hypothesis, however, the mean rates of photosynthesis for the angiosperm and gymnosperm in the cold climate (which were -.3921 and -2.327 ppm/min/g, respectively) were indeed found to be significantly different; the gymnosperm rate of photosynthesis was significantly greater in cold climate than that of the angiosperm with a p-value of 0.0490.

Gymnosperms - The Gymnosperm Database

The results are consistent with the predictions based on the hypothesis, meaning that the hypothesis cannot be rejected. However, the experiment was far from perfect and the results obtained could also be indicating a lot of other factors. There were many sources of error that were not accounted for in the experiment which could have also contributed to the results obtained. One major source of error was the fact that only one type of angiosperm and only one type of gymnosperm were used in the experiment. There were also not enough repetitions of the trials in order to obtain a decent mean. If a variety of types of angiosperms and gymnosperms were used, and if each type underwent the procedures numerous times, more accurate mean rates of photosynthesis could have been obtained. Another source of error that was extremely interesting was the fact that the gymnosperms exhibited no activity (neither CO2 consumption nor respiration) for the first 20 minutes when a light was shown on them. The gymnosperms were acting as if they were asleep! Perhaps the reason that the gymnosperms maintain their green color in the winter is because of the possibility that they may go dormant in the winter time to conserve energy, much like hibernation; the green color is just the pigment being stored in the plant. It is interesting to note that the samples of gymnosperms were both from bushes that were in total shade; the location of the plant sources is another source of error. Another source of error could be the fact that plant hormones were acting along with photosynthesis. Ethylene, for example, is responsible for leaf abscission in angiosperms. Despite all these sources of error, however, the results obtained in this lab support the hypothesis that gymnosperms have significantly higher rates of photosynthesis than do angiosperms in colder climates. These results are different from those on the CABLE webpage; those students found no significant difference between mean rates of photosynthesis in angiosperms and gymnosperms in cold weather. Perhaps they used different types of plants than were used in this experiment, which would support the idea that these results were only obtained for these specific types of plants, and are not repeatable when using other types.

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