Photosynthesis - a way of converting energy from Sunlight into chemical energy that is stored in bonds of sugar and then into ATP by cellular respiration. ATP is the "fuel" of all living things. It is used by plants, trees, protistans (algae), and some bacteria. The conversion of sunlight into chemical energy is done by a pigment called Chlorophyll. In plants and trees, photosynthesis is mostly done in the leaves, with very little done in the stem.

Cellular Rspiration - the process of making ATP from chemical energy. In the process, oxygen is consumed and carbon dioxide is generated. It is the process of oxidizing food molecules, like glucose, and turning it into carbon dioxide and water. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration. Glucose, however, is the most produced.