Which metabolic process leads to energy release in living cells?

The metabolic process that leads to energy release in living cells is respiration. This process involves the biochemical breakdown of glucose and other nutrients in the presence of oxygen (aerobic respiration) or, in some cases, without oxygen (anaerobic respiration) to produce adenosine triphosphate (ATP), which is the primary energy carrier in cells. During respiration, glucose is oxidized, resulting in the release of energy that is stored as ATP, which can be used for various cellular activities, including muscle contraction, active transport, and biosynthesis.

While photosynthesis is essential for energy capture in plants and some microorganisms, it primarily converts solar energy into chemical energy stored in glucose, rather than releasing energy. Digestion is a preparatory process that breaks down food into smaller molecules but does not directly release energy; instead, it provides substrates for metabolism. Fermentation is a form of anaerobic respiration that also releases energy but is not as efficient as aerobic respiration and is typically used when oxygen is limited. Thus, respiration stands out as the key process for energy release in living cells.