What type of product commonly uses yeast as a leavening agent?

Yeast is commonly used as a leavening agent in breads because it ferments and produces carbon dioxide gas as it consumes sugars. This gas gets trapped in the dough, causing it to rise and develop a light, airy texture characteristic of bread. The fermentation process also contributes to the flavor and aroma of the bread.

In contrast, cakes generally use baking powder or baking soda as a leavening agent, while pasta is typically made without any leavening agents as it relies on the strength of gluten for structure. Cookies tend to be denser and also make use of chemical leaveners like baking soda or baking powder rather than yeast. This makes bread the clear choice when considering leavening agents associated with yeast.