What does Saccharomyces cerevisiae (Baker’s yeast) need to survive?

Food (Sugars)

Explanation:

S. cerevisiae feeds on sugars for energy, in the process producing carbon dioxide and alcohol (this is fermentation in a nutshell). The carbon dioxide bubbles get trapped in the dough, creating the lift that makes the dough rise. The alcohol, meanwhile, evaporates when baking, transforming into gas that also contributes to the rise of the bread. The alcohol, along with acids produced during the fermentation process, impart that wonderful flavor and aroma associated with yeast-leavened breads.