The process of extracting energy from food without oxygen is called anaerobic respiration. This metabolic process allows organisms to generate energy in low-oxygen environments, utilizing compounds other than oxygen as electron acceptors. In humans, anaerobic respiration primarily occurs during intense exercise when oxygen supply is insufficient, resulting in the production of lactic acid. Other organisms, such as yeast, perform alcoholic fermentation, producing ethanol and carbon dioxide. Anaerobic respiration plays a vital role in various ecological systems and has significant implications in fields such as bioenergy and food production.