Which term best describes the entire set of biochemical reactions in an organism?

The term that best describes the entire set of biochemical reactions in an organism is metabolism. This encompasses all chemical processes that occur within living organisms, including the breakdown of nutrients to produce energy (catabolism) and the construction of cellular components from simpler molecules (anabolism). Metabolism is a broad term that reflects the balance and integration of these processes to maintain life and support growth, reproduction, and response to environmental changes.

Catabolism, while important, refers specifically to the processes that break down molecules to release energy. Anabolism focuses on the building up of complex molecules from simpler ones, which is only one aspect of metabolic function rather than the entire system. Homeostasis refers to the maintenance of stable internal conditions in an organism, but it does not specifically describe the biochemical reactions. Thus, metabolism is the most comprehensive term that captures the entirety of an organism's biochemical activity.