What term describes all chemical reactions that occur within an organism?

The term that encompasses all chemical reactions within an organism is metabolism. Metabolism includes a vast array of processes that organisms use to convert food into energy, sustain bodily functions, and maintain homeostasis. This term encompasses two main types of pathways: anabolic pathways, which build up substances (for example, synthesizing proteins from amino acids), and catabolic pathways, which break down substances (for example, the breakdown of glucose for energy).

By encompassing both these pathways and all associated reactions, metabolism provides a comprehensive framework for understanding how organisms manage energy and materials. Other terms like bioenergetics specifically focus on energy transformations within biological systems, but do not cover the wider range of reactions that metabolism includes. Therefore, the most accurate term to describe all chemical activities in an organism is metabolism.