Define "respiration." Why is respiration under aerobic conditions so much more favorable to an organism than respiration under anaerobic conditions; why do humans, and most organisms, depend on aerobic respiration? What two functions does the "respiratory system" carry out in the body?
Respiration is the breakdown of nutrient compounds into energy. While respiration without the presence of oxygen leaves relatively intact large energy-containing molecules such as lactic acid and ethyl alcohol, respiration in the presence of oxygen make possible the complete oxidation of nutrient compounds into carbon dioxide and water. In fact, ninety percent of the energy yield from the respiratory breakdown of nutrients depends on the existence of aerobic conditions. As the human body requires large amounts of energy to carry out its life activities, humans, as do most organisms, depend on aerobic respiration. The respiratory system carries out the functions of oxygen procurement and carbon dioxide elimination that are so necessary in maintaining aerobic respiration.
