| Term | Definition |
| cellular respiration | the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen |
| NAD+ | electron carrier involved in glycolysis |
| fermentation | releases energy from food molecules by producing ATP in the absence of oxygen |
| anaerobic | does not require oxygen |
| aerobic | does require oxygen |
| Krebs Cycle | second stage of respiration where pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions |
| electron transport chain | uses high-energy eltrons from the Krebs cycle to convert ADP into ATP |