Science Experiment-Balloon Yeast

In science, somewhere a month ago, we had our science experiments in yeast since our science topic that week was about cells. We wanted to find out if yeast could grow without energy. So, here is what we need:

50ml Conical Flask

two 50ml conical flasks
hot water
a beaker
a Bunsen burner
a thermometer
a teaspoon of yeast and sugar
two balloons
measuring tape
a stopwatch.

Here are the steps.

First, pour 60ml to the beaker and heat it with the Bunsen burner. Using the thermometer, observe the temperature of the water. When it reaches 38 degree Celsius, stop heating.
Second, pour 30ml of heated water into each conical flask. Name one flask FLASK A and the other one FLASK B.
Then, add a teaspoon of yeast to both of the flasks.
After that, add a teaspoon of sugar in FLASK B ONLY.
Lastly, cover up the mouth of each flasks with the balloon immediately to prevent losing the water heat.

Then, we observed for 5, 10 and 15 minutes.
We measured the distance around the widest part of the two balloons.

It should look like the picture on the left for FLASK B.
Why only FLASK B?

Budding in yeast cells

Here is the explanation.

To grow and divide, yeast cells need energy. Sugar is the source of energy. Then, it will produce carbon dioxide and alcohol, which makes the balloon inflate.

Unfortunately, in my group's experiment, our balloon did not inflate as it was supposed to. But at least, we've tried :D

-Glenn-

*note that some of the images are taken from other websites. thx