Respiration is the process in which the cells of an organism obtain energy by combining oxygen and glucose, resulting in the release of carbon dioxide, water, and ATP (energy). Respiration process that occurs in the presence of oxygen is called aerobic respiration, generally seen among humans. But in individual organisms like bacteria and algae, respiration occurs in the absence of oxygen, called anaerobic respiration. The mechanism of breathing involves various respiratory structures such as the windpipe, lungs, and nose. Respiration, on the other hand, is a chemical process that takes place in the cell.