CP Maya and Meredith

Introduction- Meredith

1. Background
   1. Fermentation is the chemical breakdown of a substance by bacteria, yeasts, or other microorganisms, typically involving effervescence and the giving off of heat. In this lab, students studied fermentation using yeast. Yeast is classified in the kingdom Fungi and is most popularly known for its effects on bread. The purpose of this lab was to present the effects of fermentation in a way students could easily observe. We were asked to create experiments and record our data observed. Fermentation is very important to life, as students learned through this yeast lab.
   2. Experimental Design
      1. How will the rate of fermentation of yeast cells change if the amount of sugar is altered as well as the temperature? The independent variables in this lab are the temperature levels and the sugar amounts. The dependent variable was the foam levels from fermentation. We measured the dependent variable in centimeters, and the independent variables were both measured in milliliters. The control in this experiment was a test tube with three grams of yeast combined with 25 milliliters of lukewarm water and 1.5 milliliters of sugar, left to ferment for ten minutes.
   3. Hypothesis
      1. If the water is warmer and the sugar levels are higher, the more the yeast will ferment, causing more foam.

Methodology and Procedure- Maya

1. For this lab we experimented with how different sugar levels and temperatures would affect the fermentation of yeast. To test this we put 3 grams of yeast into a test tube and added a liquid. This was mixed and then we either added sugar to the solution, or let it begin to ferment. We let each mixture ferment for ten minutes before measuring the amount of foam that the yeast produced. We used four different solutions and repeated each solution three times.
   1. For the first solution, we used 25mL of cold water and added 3 grams of yeast. This was mixed together, and then 1.5 mL of sugar was added. The solution fermented for ten minutes and was then measured. This process was repeated three times. The yeast grew an average of 1 cm.
   2. The second solution was 25 mL of hot water with the same 3 grams of yeast and 1.5 grams of sugar. The solution was mixed and allowed to ferment for 10 minutes. The average growth of this solution was 10 cm.
   3. The third solution was 25 mL of cold soda and 3 grams of yeast. No sugar was added to this solution. The solution fermented for 10 minutes. The yeast grew an average of 0.5 cm.
   4. The final solution was 25 mL of hot soda and 3 grams of yeast. No sugar was added to this solution and it was allowed to ferment for 10 minutes. The average amount of growth for the yeast was 9 cm.

Data and Results- Meredith

1. Three grams of sugar were added to the hot/cold water tests. No sugar added to either soda test. Yeast did not ferment well under cold temperatures. Yeast fermented the most under hot water with 3 mL of sugar. Foam production was the highest during the last 4-5 minutes of the tests.
2. 

Discussion and Analysis- Maya

1. The results in this lab were somewhat expected, and supported the hypothesis. We predicted that the yeast would grow better in a warmer solution, which was supported by the experiments conducted. This experiment shows that yeast grows better in warmer solutions, and does not grow well in cold solutions. The experiment also proved that sugar types do not affect yeast growth as much as temperature. Both regular white sugar and high fructose corn syrup were used, and the yeast growth only differed by about 1 cm.

Works Cited

1. Miller and Levine. Biology. N.p.: n.p., 2010. Print.