Wednesday, March 23, 2011

Yeast Beasts in Action Lab Investigation

How does yeast react with different mixtures of neutral, basic, and acidic substances?My hypothesis was "If we test yeast's reaction with different mixtures, then the basic one will react the most."
Here is my data:


Highest Pressure


122.13 kPa


117.81 kPa


128.32 kPa

To conduct this experiment, you will need the following:
Vernier computer interface
Vernier Gas pressure sensor
1-hole stopper assembly
10 mL graduated cylinder
3% hydrogen peroxide
yeast suspension
3 test tubes
test tube rack
acidic mixture (diet soft drink)
neutral mixture (skim milk)
basic mixture (stomach antacid)

This is what happened inside the test tubes:
The yeast reacted with the diet soda, the skim milk, and the stomach antacid inside the test tubes. Have you ever watched bread rise? The rising bread is caused by the yeast. So this rising process happens when yeast is introduced to certain substances. If the reaction happens in an enclosed environment or container, the pressure will build because the gas from the rising elements is trying to rise, but is getting trapped.

1. In which mixture was the yeast activity greatest? In the stomach antacid (basic) mixture, it was the most pressure (128.32 kPa).

2. In which mixture was the yeast activity least? In the skim milk (neutral) mixture, it was the least pressure (117.81 kPa).

3. What can you conclude from the results of your experiment? I can conclude that basic substances react more with yeast, while neutral and acidic mixtures do not.

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