Cellular respiration is a chemical reaction in which the potential energy stored in the chemical bonds of glucose, is converted into molecules of A.T.P., the energy currency of the cell. The first step is called the anaerobic phase. Oxygen is not needed for it to proceed. It occurs in the cytoplasm of the cell. Glucose is broken down into two pyruvic acids with the release of 2 ATP. The second step is the aerobic phase and oxygen is needed for it to proceed. This step occurs in the mitochondria--the powerhouse of the cell. Glucose is completely broken down into 34 ATP with the wastes water and carbon dioxide are produced and must be excreted. The net gain of ATP is 36 molecules, which the cell uses for its metabolism and growth and life activities. Anaerobic respiration in microorganisms like certain bacteria and yeast is known as fermentation. Along with the release of 2 ATP, yeast produce alcohol and carbon dioxide as wastes. Bacteria produce lactic acid and carbon dioxide as wastes. Transpiration is the process by which excess water evaporates out of the stomates of green plants. This water is in the form of water vapor and is one of the ways water enters the atmosphere during the water cycle.