Question

Yeast Fermentation Results

1. Clearly stated hypothesis
2. Identify the independent and dependent variables
3. Your conclusion as to the sugar which produced the highest rate of fermentation by the yeast, citing evidence from the video to support your conclusion.
4. Was your hypothesis supported by the experimental data? Provide a biological explanation for the results that you observed.

Answer 1

The different types of sugars used in fermentation had a significant impact on the amount of carbon dioxide produced. Glucose produced the most with a gas bubble of 132mm while sucrose yielded 102mm of carbon dioxide. The gas by product in fructose measured only 56mm.The control with no sugar resulted in 0mm of carbon dioxide and was the least productive of the tubes. The slope of the line of best fit was analyzed to determine the average rate of carbon dioxide production over the 20 minute time frame. Glucose was the most efficient, producing12.64 mm of carbon dioxide per minute. Sucrose yielded 9.27 mm of carbon dioxide per minute during fermentation while fructose functioned at a rate of 3.99 mm of carbon dioxide per minute. The control that contained no sugar had no rate of carbon dioxide production. The rate of production of carbon dioxide for both glucose and sucrose remained fairly constant throughout the experiment. The rate for fructose began slowly but increased rapidly as time went on. The rate of production of carbon dioxide remained at a constant 0 throughout.

Discussion & Explanation:

The hypothesis was supported in that all forms of sugar produced energy and that glucose was the most efficient. The carbon dioxide produced can be directly related to the energy produced through fermentation because carbon dioxide is a by-product of ethanol fermentation. The control that contain no sugar produced no energy because a source of sugar is required for glycolysis and fermentation to occur. Glucose had the greatest rate of energy production because its rate of carbon dioxide production was the largest. Sucrose had the second highest rate of production while fructose had the lowest rate out of the three sugars. Glucose’s rate of energy production was more than three times that of fructose.

Reason why glucose shows highest fermentation rate and best sugar for fermentation in yeast:-

Glucose was directly used in the glycolysis cycle and did not require any extra energy to convert it into a usable form. This supported why glucose was the most efficient. Sucrose required an enzyme and energy input to break it down into glucose and fructose in order for it to be processed in glycolysis. Fructose also could not be used immediately in the glycolysis chain but had to be altered to enter the chain as one of the intermediates. These processes required to convert the non-glucose sugars into a usable form reduced their efficiency when compared to glucose.