Aerobic respiration takes place in the presence of oxygen, while anaerobic respiration takes place when no oxygen is present, according to New Health Guide. Both aerobic and anaerobic respiration refer to breakdown of glucose that takes place on a cellular level.
New Health Guide explains that the process of cellular respiration is crucial for the production of energy molecules known as adenosine triphosphate (ATP). New Health Guide states that when oxygen is present in the cells, ATP is produced through oxidative breakdown of glucose (sugar), with carbon dioxide and water created as by-products of the process. If there is no oxygen present, glucose is broken down into ATP and lactic acid as a by-product. According to New Health Guide, less energy is released under anaerobic respiration.