Yeast Beasts in Action Investigation

How much pressure will yeast create when mixed with an acid, base and neutral?

Hypothesis: The yeast will have more pressure in the base because the acid will break down the yeast particles and the neutral will keep the pressure level pretty much the same.

Materials:
-Hydrogen Peroxide (HP)
-Soda
-Antacid
-Milk
-Yeast
-Dropper
-Test tube rack
-Yeast suspension
-10 mL graduated cylinder
-1 hole stopper assembly
-Computer
-Vernier Computer interface
-Vernier Gas Pressure Sensor (GPS)

Procedures:
Connect the GPS to the computer interface. Start the Vernier data-collection program and open the file "24 Yeast Beasts" from the Middle School Science with Vernier folder. Next, place 3 test tubes in a test tube rack and label them A, N, B (acid, neutral, base respectively). Add 3 mL of HP and 3 mL of each mixture (A, N, B) to its test tube. Next, the yeast suspension need to be made. Fill a beaker with 20 mL of water and then pour 1/2 teaspoon into the beaker and the suspension system is made. After this, add 2 drops of yeast (roughly 1 mL) into Test Tube A. Insert the 1-hole stopper assemble into the test tube. Twist the stopper for an AIRTIGHT fit. The plastic tubing should not yet be attached to the stopper assembly. Swirl the tube to thoroughly mix its contents and stand the test tube in the rack. Connect the free end of the plastic tubing to the connector in the rubber stopper. Click "Collect" to begin data collection. Data will be collected for 2 minutes. Don't shake the test tube during data collection. When collection ends, record the highest pressure for this run. Click "Story: from the experiment menu to store your data. Disconnect the tubing from the rubber stopper and remove the rubber stopper from the test tube. Repeat these steps with Test Tube N and Test Tube B.

Results:
Acid:
Initial Pressure: 100.2 kPa
End Pressure: 106.2
Neutral:
IPressure: 99.5
EPressure: 104.1
Base:
IPressure: 99.9
EPressure: 106.7

It turns out that my hypothesis correct. Out of the three test tubes, the base had the most pressure. When the data was collecting, the base looked like it was going to lose by a very short margin to the acid, but luckily it pulled through. (For diagrams and pictures, ask to see them. They didn't want to insert.) I knew my hypothesis was right for many reasons. First of all, I knew about the properties of acids. The purpose for stomach acid is breaking down food particles to speed up digestion. I knew that the soda would have the same effect. Second, I knew what would happen when a neutral was introduced. When something is diluted with water, it usually means that the first liquid loses some or all of its properties. Thanks to this background knowledge, I was able to make a good hypothesis that turned out right. I think this is the first time I was ever right for a lab.