Yeast is a fungus with a life cycle that humans have been taking great
advantage of for thousands of years.
Yeast eats carbohydrates, like sugar or grain, and produces alcohol and
carbon dioxide gas.
We put yeast in our flour dough, and the carbon dioxide poofs up the
dough to make bread.
We put yeast in soups of various fruits and vegetables, and the alcohol
turns it into wine or beer.
