Final answer:
Respiration is the exchange of oxygen and carbon dioxide between an organism and its environment, integral to both the function of the respiratory system and cellular metabolic processes. Aerobic respiration requires oxygen supplied by autotrophs through photosynthesis and releases carbon dioxide.
Step-by-step explanation:
The exchange of oxygen between an organism and its environment is known as respiration. This biological process involves external respiration, which is the actual exchange of gases (oxygen and carbon dioxide) between the atmosphere and the organism's blood through the lungs or gills. It is essential to distinguish respiration from cellular respiration, though they are closely related. Cellular respiration is the metabolic process where cells produce energy (ATP) by metabolizing glucose in the presence of oxygen. Organisms rely on this oxygen to perform aerobic respiration, which includes both the exchange of gases in the respiratory system as well as the cellular breakdown of organic molecules. Autotrophs contribute to this cycle via photosynthesis, supplying the excess oxygen heterotrophs use in respiration while utilizing the carbon dioxide produced by heterotrophs during the respiration process.