What is similar to baking powder?

* Baking soda is a leavening agent that, when combined with an acid, releases carbon dioxide gas. This gas causes baked goods to rise. Baking soda is similar to baking powder in its leavening action. However, baking soda requires an acid to be activated, while baking powder contains both an acid and a base. Therefore, baking soda is not a direct replacement for baking powder, and the recipes that call for one should not be used with the other.

* Yeast is a fungus that produces carbon dioxide gas as a byproduct of its metabolism. This gas causes bread and other baked goods to rise. Yeast is different from baking powder and baking soda in that it is a living organism and requires time to grow and produce gas.

* Sourdough starter is a fermented dough made from flour and water. It contains a variety of microorganisms, including yeast and bacteria, which produce carbon dioxide gas. Sourdough starter is used to leaven bread, and it gives bread a characteristic tangy flavor.