Getting Energy From Food All organisms must break down food molecules to release the stored energy.

2 Ways to Break Down Food 1. Cellular Respiration (uses oxygen) Breathing supplies your cells with the oxygen they need to perform cellular respiration. It also rids your body of carbon dioxide, which is a waste product of cellular respiration.

Food is broken down into CO2 and H2O, and energy is released. Some energy is stored as ATP. Most energy is released in the form of heat. (homeostasis – maintaining a stable internal environment) Cellular respiration takes place in the mitochondria.

Chemical Equation for Cellular Respiration C6H12O6 + 6O2  6CO2 + 6H2O + energy (ATP) Glucose + Oxygen  Carbon Dioxide + Water + Energy (ATP)

2. Fermentation (Does not use 02) Leads to the production of a small amount of ATP and products from the partial breakdown of glucose.

2 Types of Fermentation A) Occurs in muscles; produces lactic acid, which contributes to muscle fatigue after strenuous activity. Also occurs in some types of bacteria. B) Occurs in certain types of bacteria and in yeast. Yeast cells make carbon dioxide and alcohol during fermentation of sugar. Carbon dioxide causes bubbles to form in bread.