Expert: Dana Krempels, Ph.D. - 9/24/2008

Question
ok so in my advanced biology class we had to make our own lab with yeast and i choose to test whether tap or distilled water made a difference but for background information i don't know what really the difference or why yeast react to either one help me please!!!!

Answer
Dear Kristin,

Since this is a school project, I cannot answer it for you.  But I can give you some hints.

Consider that distilled water has no ions in it, and consider the osmotic pressures that this would cause for the yeast, whose cells contain lots of substances.  Which direction do you expect the water to move without any "action" on the part of the yeast?  And in light of this, why might distilled water be dangerous for yeast?

Also consider the potentially toxic ions in tapwater (e.g. chloride), and then create some hypotheses about what you should expect to see in each type of solution.

Good luck,

Dana