How is water used indirectly as a leavened?

Water is used indirectly as a leavening agent in the process of hydration within dough. When flour is mixed with water, it activates enzymes that convert starches into sugars, providing food for yeast. The yeast ferments the sugars, producing carbon dioxide gas, which causes the dough to rise. Thus, while water itself does not leaven, it facilitates the necessary biochemical reactions that enable leavening through yeast activity.