Yeast Beasts in Action Lab Investigation

Today, we worked on a lab that would test the pressure of different solutions and yeast. The three solutions that we tested were an acid (Diet Coke), A Neutral (Milk), and a Base (Stomach Antacid). My hypothesis was that the most acidic would react the most, my hypothesis was incorrect. The yeast reacted most with the base. I think that this is because the two reactants are more reactive together than with any other mixture. Here are some pictures of the investigation:

 

There were some questions involved in the lab and here they are:
1) In which mixture was the yeast activity greatest? A: The most basic of the mixtures.

2) In which mixture was the yeast activity least? A: The most neutral of the mixtures.

3) What can you conclude from the results of your experiment? A: I can conclude that basic mixtures are the most reactive with yeast.