What do you add to bread to make it rise?

Explanation

Yeast for baking was first used in ancient Egypt some 5000 years ago. Yeasts are fungi which are found everywhere in nature. When yeast fungi are in an environment that is sugar-rich, they expand quickly. Through this proces CO2 is produced, which makes a bread or a cake rise. CO2 is the same gas that is exhaled by humans every time they breathe.