AP BIOLOGY

Detailed explanation-1: -Carbon dioxide is the main gas associated with yeast leavened bread, however, other gases that play a role are ethanol, nitrogen and steam.

Detailed explanation-2: -Carbon dioxide from yeast fills thousands of balloonlike bubbles in the dough. Once the bread has baked, this is what gives the loaf its airy texture.

Detailed explanation-3: -Excess yeast causes extra air bubbles to form, creating holes in the baked bread.

Detailed explanation-4: -Once reactivated, yeast begins feeding on the sugars in flour, and releases the carbon dioxide that makes bread rise (although at a much slower rate than baking powder or soda).

Detailed explanation-5: -This carbon dioxide helps in the rising of the dough. When this dough is subjected to high baking temperatures, carbon dioxide escapes from the dough resulting in soft and fluffy bread.