What is the process by which cells are nourished in living organisms?

The process by which cells are nourished in living organisms is best characterized by metabolism. Metabolism encompasses all the biochemical reactions that occur within cells to convert food into energy and utilize it for cellular growth, repair, and maintenance. This includes both catabolic processes, which break down molecules to release energy, and anabolic processes, which build up complex molecules from simpler ones.

In essence, metabolism is fundamental because it ensures that cells have the necessary nutrients and energy to function properly, thus supporting overall organismal health. It involves the absorption of nutrients through digestion, but its scope is broader as it also includes the entire network of reactions and pathways that enable cells to handle these nutrients effectively.

While respiration involves the exchange of gases and is vital for energy production, it is merely one part of metabolism rather than the entire process of cell nourishment. Digestion is focused specifically on breaking down food into absorbable components but does not encompass what happens to these nutrients at the cellular level. Reproduction refers to the biological process of producing new organisms, which is unrelated to how cells are nourished. Therefore, metabolism stands out as the comprehensive process that truly represents how cells obtain and utilize nourishment.