Lab Exercise 7
The Effect of Temperature on the Rate of Carbon Dioxide Production in Saccharomyces
I. Student Objectives 1. The student will use this lab exercise as the basis for writing a scientific method report. 2. The student will understand how the rates of chemical reactions are affected by temperature. 3. The student will understand the overall fermentation reaction by yeast, starting with glucose as an energy source. 4. The student will understand how to measure fermentation rate.
The student is to use this lab exercise as the foundation for writing a scientific method report. The instructions for writing the report are found in the …show more content…
This absolutely insures there will be enough yeast, and that the reaction will proceed rapidly. Place each tube in a water bath at the appropriate temperature, and record the START time. Allow to ferment (form gas bubbles) until ¾ of the closed end of the tube has been filled with carbon dioxide. In the case of slow or non-reactions, keep in water bath as long as possible, leaving enough time to complete the following sections. When ¾ of the closed end of the tube has been filled with gas, mark the level with a red marking pencil, and record the END time. Calculate the difference between start and end times, noting how much time each fermentation tube remained in the water baths. Pour out the yeast solution, fill the closed end of the tube with water to the mark, pour into a graduated cylinder, and record the volume in milliliters. The rationale is that gas cannot be measured directly in the lab; water, however can be measured to the mark, and can serve as an indirect measure of gas production. Calculate the rate of carbon dioxide production by dividing the volume of the gas produced by the time. Dimensions are ml/min. There are 5 values, one for each of the 5 water bath temperatures. This is the data that should appear on a graph, marked Figure 1. Calculate the temperature co-efficient value of Q10. This is done for four temperature intervals. Start with the two lowest temperatures, 250 and 350 C. The temperature co-efficient is a