Yeast Fermentation Lab Report
Present to Ms.Allinotte November 21. 2014
Introduction: Fermentation is a metabolic pathway that produce ATP molecules under anaerobic conditions (only undergoes glycolysis), NAD+ is used directly in glycolysis to form ATP molecules, which is not as efficient as cellular respiration because only 2ATP molecules are formed during the glycolysis. One type of fermentation is alcohol fermentation, it produces pyruvate molecules made by glycolysis and the yeast will break it down to give off carbon dioxide, the reactant is glucose and the byproducts are ethanol and carbon dioxide. In this lab, the purpose is to measure whether the changes of substrate concentration will affect the rate of anaerobic respiration. Because the rate of reaction refers to how quickly the reactants are used up or how quickly the products are formed, one method is to measure the volume of gas given off, the more gas given off per time interval results faster reactions.
Question: Will the changes in substrate concentration affect the rate of anaerobic reaction? Why or why not? What are the independent variable and dependent variable in this lab activity? What are some other controlled variables?
Hypothesis: If substrate concentrations are changed, then as the concentration increase, the rate of anaerobic reaction will also increase, because the increase of the reactant concentration means there are more reactant particles, and there is a greater chance for these particles to collide and let reaction happen. The independent variable is the concentration of the substrate, and the dependent variable is the one will be measured, which is the volume of gas. The controlled variables are the temperature, the amount of yeast and water.
Three envelopes of active dry yeast
Three 500 mL bottles
Three Balloons (Medium-sized)
References:  Boundless Chemistry,(2014) ‘The collision Theory.’retrieved fromwww.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/chemical-kinetics-13/activation-energy-and-temperature-dependence-100/the-collision-theory-422-7067/on 22.Nov.2014  Helen K. Pigage, Lt. Col. Milton C. Neilsen and Michele M. Greeder.(1998) ‘Using Yeast Fermentation as a Model for Scientific Method’.