Final answer:
Energy flows through aerobic conditions via the process of aerobic respiration in the mitochondria, producing ATP with the help of oxygen and inputs such as glucose and fatty acids. The efficiency of this process is evidenced by the high yield of ATP compared to anaerobic processes, which are used when oxygen is not available.
Step-by-step explanation:
Under aerobic conditions, energy is primarily extracted during aerobic respiration which occurs in the mitochondria. The process uses inputs such as glucose, pyruvic acid, and fatty acids. Aerobic respiration is significantly more efficient than anaerobic glycolysis, yielding about 36 ATP molecules compared to only four ATP molecules with glycolysis. For this process to continue, there must be a continuous supply of O2 (oxygen).
Oxygen is crucial as it acts as the terminal electron acceptor in the electron transport chain, the final stage of aerobic respiration, which coupled with the chemiosmotic gradient effects through ATP synthase, is responsible for the production of a majority of the ATP. Myoglobin present in muscles stores excess oxygen to facilitate efficient muscle contractions, while aerobic training enhances the circulatory system's ability to supply oxygen over longer periods.
Different from aerobic respiration, in the absence of oxygen, organisms may resort to fermentation processes such as alcohol fermentation or lactic acid fermentation, to continue producing ATP and regenerating NAD+. This alternative pathway is crucial in producing products like yogurt and soy sauce and in preventing muscle cramp during vigorous exercise.