Conclusion


 * Conclusion**

-//Limitations of the Experiment//: There were many limitations of this experiment preventing it from being ideal. There was a great deal of error involved. The non-electronic instruments were one cause of error: the graduated cylinders were not completely accurate, causing uncertainty in the reading for how much water was displaced. Another issue was the fact that the rubber stoppers were not completely airtight, so other gases could potentially enter and disrupt the reading. Overall, the non-electronic instruments may have been slightly flawed, but nonetheless did not have too much of an effect on our results. However, the computer instruments were the main source of error. The scale used to measure glucose and yeast was not completely accurate, potentially causing differing amount of yeast in each solution and changing the results. The water temperature probe was also not completely accurate, so different water temperatures were used in the experiment. A major problem was the error of the CO2 probes, which led to erroneous readings of CO2 levels. This was a significant drawback, since it prevented us from using computer-generated data, and instead we had to rely on non-computer generated data. We made a couple mistakes during the experiment. One mistake was measuring how much time had elapsed. We did not have a stopwatch, and instead had to look at the analog clock, so readings were not always at even intervals when they could have been. This did not affect the result, however, since all readings were done simultaneously, and the time interval in between was irrelevant. Another mistake made was that the first time we conducted the experiment, we forgot to incubate the yeast, and were forced to repeat the tests in order to achieve proper results.

-//Summary/Interpretation//: Ultimately, we confirmed our alternative hypothesis and falsified our null hypothesis. In the non-computer generated data set, we found that solutions with more grams of glucose displaced more milliliters of water than solutions with fewer grams of glucose, suggesting that higher levels of glucose relate to faster rates of cellular respiration. We also observed that yeast without any glucose did not displace any water, suggesting that without glucose, yeast cannot respire. In the computer-generated data set, our findings seemed to contradict our previous results. The latter data set showed that yeast without any glucose caused the greatest increase in CO2, and the yeast with 10 grams of glucose caused the least increase in CO2. It would be inferred from this data that lower levels of glucose cause faster rates of respiration, and that yeast with no glucose can still respire. We concluded that this data was invalid for a couple of reasons (explained in depth in results page): logically, yeast with no glucose cannot respire, there was an unexplained spike in the graph which could not be the result of respiration, and also the amount of CO2 in the 10g solution decreased over time, which does not make sense in the reaction of cellular respiration. Finally, we settled on the non-computer generated data, since there was overall less error, and the results were more logical. Our answer to the question we posed at the beginning of the lab is that glucose does affect the rate at which cellular respiration of yeast occurs, causing it to increase when more glucose is available.

-//Further Study//: For future experiments, we would suggest measuring the effects of glucose on the respiration of yeast in anaerobic environments. This could be useful in the wine and bread industries, since yeast respiration occurs under anaerobic conditions in making these products. Another study we would suggest conducting would be to find what other sugars, besides glucose, yeasts are capable of using to respire. A final suggestion for future experimentation would be using different types of yeast and seeing which are most effective. These findings could be added to our own, and could be useful in the wine and bread industries to find the most effective types of yeasts and sugars.

-//Application//: Our experiment has considerable applications in the wine and baking industries, as mentioned before. In the introduction, we mentioned the species of yeast //Saccharomyces cerevisiae////. This species is usually used to make bread, wine, and beer. When making wine, the yeast are placed in vats with one-way valves which keep air out from the vat, but allow CO2 to escape. When Saccharomyces cerevisiae//// are in these vats, they are in an anaerobic environment, and release ethyl alcohol to ferment the wine or beer. Although our // experiment was conducted in an aerobic environment, our reasoning would still apply to an anaerobic environment, meaning that most likely higher levels of glucose will cause the wine to ferment faster, which could be important in the wine industry. When making bread, the yeast consume glucose and release CO2, causing the dough to rise. Our experiment suggests that by adding glucose, bakers could accelerate this process. Overall, our experiment has many practical applications in these fields.