It is the action of the yeast that causes breads to rise. Yeast as it grows produces carbon dioxide this is trapped in the bread dough and causes the dough to rise.
Leavening with yeast is a process based on fermentation, biologically changing the chemistry of the dough or batter as the yeast works. Yeast leavening requires proofing, which allows the yeast time to reproduce and consume carbohydrates in the flour.
Yeast. The little cells of yeast can digest sugar and starch. This gives off carbon dioxide gas, filling bubbles in the dough and giving it a foamy texture (that is, leavening it). The other byproducts are various alcohols and other organic solvents. These are driven off in baking, giving baking bread its distinctive aroma.
Yeast is used in many leaven breads. However, many breads use other leavening agents such as baking soda. Other breads use no leavening agent at all; these include matzo, flatbreads, tortillas, cornbread.
Leavening agents are the ingredients that make the baked goods rise so they are light and airy. It could be yeast, baking soda, or baking powder. Sometimes in cakes, the eggs are whipped into a froth to add air to the cake and this acts as a leavening agent.
Yeast is called a leavening agent. The growing yeast produces carbon dioxide which collects in the dough and makes the bread rise. With out a leavening agent bread would be flat
They are chemical (non-yeast) leavening agent usually used in quick breads, cakes and cookies.
The leveling agents such as baking powder/soda in quick breads and in normal breads, the yeast 2nd answer: That should be 'leavening agents'.
The leavening of bread is the ingredient which aids in the rising process. Yeast is the typical leavening agent used to make bread. Depending on the bread, there are variations of yeast to choose from including active dry yeast and quick-rise yeast.
Yeast.
It really depends on what the flour/leavening agent/liquid mix is for. Most commonly, using something like that would be known as a poolish for making bread (flour, yeast, and water). However in making quick breads and cakes, there is no specific name for it. (Reference: Baking+Pastry Arts Graduate)
Leavened bread contains a leavening agent (such as yeast, though others may be used) that makes it rise. Unleavened breads do not. Typically, leavened breads are lighter in texture, whereas unleavened breads are denser and flatter.
Yeast is used as a leavening agent. The product, bread, will have a softer and lighter result
Most are made using bakers yeast as leavening, however some loaves (called "sourdoughs") are made without any added yeast whatsoever.
The function of leavening agents is to cause the baked goods (breads, cakes, etc.) to rise. There are different types of leavening agents, such as yeast, baking powder and baking soda. Eggs are also sometimes used as a leavening agent, especially in some pound cake recipes. Without leavening, the baked goods will not only be flat, but won't taste as good, either.