Is there yeast in whole wheat bread?

Whole wheat bread typically contains yeast as a leavening agent. Yeast is a type of fungus that consumes the sugars in dough and releases carbon dioxide gas, causing the dough to rise. Some whole wheat bread recipes may use sourdough starter instead of commercial yeast, but yeast is still present in this case. Sourdough starter is a fermented dough made from flour and water that contains wild yeast and bacteria.