Because it works. The gluten content is flour makes it perfect for things that are doughy - gluten prevents doughs from falling apart (gluten-free flour is a lot like working with mashed potato - very difficult to shape and mould etc...) Also, because it is commonly available and at low cost. And it's easy to make it taste nice (it's rather bland but does not have an unpleasant taste that requires covering up).
Yes, baking powder is used in preparation of cakes, but few breads. Baking powder and baking soda are leavens, which cause them to rise. Three to four teaspoons of baking powder is used in making biscuits. But most breads have yeast, in some cases salt, to make them rise.
Baking powder is used as leavening in baked goods such as cookies, cakes, quick breads, biscuits and pancakes. It creates gas in the batter that causes the product to rise.
Most biscuits use baking powder or baking soda in baking. Biscuits are a type of quick bread. Though some cooks do use some yeast to make their biscuits rise more.
During baking the heat from the oven cooks the flour, and depending upon the ingredients used, the temperature and the duration of cooking you get a bread, cakes or biscuits as the end product
To bake cakes and to do experiments on it
Baking sugar.
baking soda is generally used in cakes recipes to make them fluffier and softer .
to make them rise
Cranberries are generally used for eating and put in puddings, cheese, biscuits, cakes etc
soul cakes
Baking powder is useful for mixing into many types of batter and dough as leavening. It already contains an acid, so it does not need additional acid in the batter, as baking soda needs. Some baked good that use baking powder as leavening are Quick Breads, Cookies, Biscuits, Cornbread, Muffins, Pancakes and Waffles.
Baking powder is a raising agent commonly used in cakes, biscuits, etc. If a recipes calls for baking powder, you should use it as it performs the important function of producing gases during the baking process which creates lift and aeration. If you do not use baking powder, where indicated, you will find that your cake will not rise or your biscuits will be flat and lifeless! There are, of course, lots of recipes which do not need baking powder. Also, self raising flour already contains a set quantity of raising agents and therefore recipes which use this as an infgredient are less likely to need further raising agents such as baking powder or sodium bicarbonate.