Question

• PROCEDURE

1. Sugar

   Fermentation

   (in yeast cells)

   Alcohol + CO2

   Place the bottom of a small funnel into the opening of the balloon. You may need to stretch the opening of the balloon a little bit so that it fits
2. Pour in the balloon:

1 teaspoon      dry yeast

1 teaspoon      sugar

10 ml                 warm water

3. Gently squeeze the balloon a few times to mix the ingredients
4. Remove the funnel from the opening of the balloon, gently express air and tie a knot in the balloon to keep the water-and-yeast mixture inside.
5. Set up a second balloon in a similar manner but skip one of the components so fermentation wouldn’t take place – it will be your “negative control”
6. Measure the circumference of both balloons in centimeters using measuring tape – it is your “0 minutes” time point for the Data Table in the LAB REPORT (p.4)
7. Place the balloons in a warm incubator (37-40^oC) and wait, measuring balloon circumferences at the indicated time points and recording the results in the Data Table of the LAB REPORT (p.4)

QUESTIONS TO ANSWER:

• What substances did you choose to place in the “negative control” balloon? Why?
• What is/are the reactant(s) in fermentation reactions? What are the products?
• Which organisms performed fermentation in this experiment?

Answer 1

1. A negative control is the one which will not give the results. It will contain sugar and water or yeast cells and water. It will not give results because all the experimental reagents are not added. Sugar is fermented by yeast cells to produce carbon dioxide and water. In the absence of either, fermentation will not take place.

2. Fermentation is the process of breakdown of glucose or any other type of sugar in the efficiency of oxygen to produce carbon dioxide and water.

3. Fermentation is carried out by organisms like yeast it is also called as Baker's yeast. Other organisms are bacteria like Lactobacillus.

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