Re: Do salt make yeast grow?

Notice that in each of your experiments you varied the amount of sugar BUT not salt. You either added salt or you didn't. Do you suppose if you repeated the experiment and included different concentrations of salt, that your results would be different? Hint - salt is requied for proper yeast growth. Without it, there might be enough salt ions in the solution to allow for limited growth. By adding salt to your solution, you provided the yeast with a factor that it requires. Did you run your experiment more than one time to prove that the amount of CO2 you observed was consistent from one experiment to another? I'm not asking this to say that what you observed was wrong, just that to prove your initial observation many trials would be required for you to feel confident with the results. In other words, following the steps of the Scientific Method(Process). There are additional considerations to take into account besides salt concentration that could contribute to the amount of CO2 produced each time. For example, the water temperature was listed as warm. But, do you know if the temperature varied in each experiment by more than a degree or two. You'd be surprised at the difference one degree can have on yeast metabolism! If you get a chance, take a look at the website provided below. I think you will find it very useful as the individual did a fairly extensive investigation on the same subject. http://walden.mvp.net/~sklib /yeast.html Good Luck, Dr. Jeffrey Stiefel