Introduction: Fermentation is a metabolic process that occurs in the absence of oxygen molecules, also known as an anabolic reaction. This is a process of glycolysis in which sugar molecules are used to create ATP. Fermentation takes many forms, the two best known examples are lactic fermentation and alcoholic fermentation (Cressy). Lactic fermentation is used in many areas, from the production of foods such as bacteria to its use by the tired muscles of complex organisms (Cressy). When you experiment with organisms such as yeast, which was done in this experiment, you follow the metabolic pathway of alcoholic fermentation (Sadava). Where sugar molecules are broken down and become ethanol (Sadava). But the end product of fermentation is the production of ATP, it helps produce a small amount of energy to maintain metabolic functions while the system in question replenishes its oxygen. Yeast cannot ferment without a substrate, the best known substrate is glucose. There are many ways to observe fermentation. Alcohol, ATP and CO2 are all measurable products of fermentation. Gas production is most easily measured with the naked eye. Showing the amount of CO2 produced can establish a relationship between fermentation rate and time. Certain factors can affect the fermentation speed, such as temperature, substrate concentration and pH level. This experiment focuses on the degree of fermentation that can occur under certain conditions. pH levels will change the rate at which the yeast ferments and produces CO2. Every biological reaction occurs at optimal levels within ranges of pH, temperature, and light, regardless of the drivers of that reaction. So we need to test every level we can think of to find that optimal range and see how they differ...... middle of paper ...... H. O'neil. LabTutor online. Np: np, nd Print. Galafassi S, Merico A, Compagno C, et al. Dekkera/ Brettanomyces yeasts for ethanol production from renewable sources under oxygen-limited and low pH conditions. Journal Of Industrial Microbiology & Biotechnology [online series]. August 2011;38(8):1079-1088. Available from: Academic Search Complete, Ipswich, MA. Accessed February 23, 2014. Huang H, Guo X, Li D, Liu M, Wu J, Ren H. Identification of crucial yeast inhibitors in bioethanol and improvement of fermentation at high pH and high total solids. Bioresource technology [online series]. 2011 Aug 15;102(16):7486-7493. Available from: Academic Search Complete, Ipswich, MA. Accessed February 23, 2014. Sadava, David E., David M. Hillis, H. Craig Heller, and May R. Berenbaum. Life: the science of biology. 10th ed. Sunderland, MA: Sinauer Associates, 2014. Web.