the carbon dioxide that is produced during fermentation expands which causes the dough to rise and the coagulation of the protein gluten prevents the dough from falling back into its original state (flat).
Bread made with a raising agent is called leavened bread or yeast bread.
yeast
bred without a yeast or a raising agent
It is the causative agent of thrush and yeast infections.
Yeast.
Levure in French means Yeast ( a raising agent used in bread, etc ).
yes. they're small living things inside of the yeast
I'm not sure what you mean by mechanical, but raising agents like baking soda, baking powder, and yeast make foods light and fluffy.
Actually, it does. It's just in very, very small amounts. There are various types of yeast in the air so some of it lands on the flour. Ages ago, it was the natural yeast in flour or in other bread ingredients that made bread rise. Now days we add the yeast to make the bread rise more predictably.
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)
By the time you get around to using the mix, the yeast will be dead and expended.
Self-rising flour (usually) has baking powder mixed into it in a certain ratio. Baking powder is used for rising baking such as cookies, biscuits, cakes, etc. It isn't appropriate for use with yeast because yeast is a raising agent. Baking powder creates gases that bubble and puff up baking by way of a chemical reaction. Yeast is a form of bacteria that eat sugar and excrete CO2, which is a gas, that puffs up baking by way of a biological reaction. If you used self-raising flour with yeast you would have two competing forms of raising agent - and I have no idea what kind of mess you'd find in your oven afterwards!