Final answer:
Metabolism refers to the total chemical changes that occur within a cell, including both anabolic reactions that build complex molecules from simpler ones and catabolic reactions that break them down to release energy.
Step-by-step explanation:
The total chemical changes that occur inside a cell are known as metabolism. The cell's metabolism encompasses both anabolic and catabolic reactions. Anabolism is the process that synthesizes and builds complex molecules from simpler ones, which requires the input of energy (endergonic). Conversely, catabolism involves breaking down complex molecules into simpler ones, releasing energy (exergonic). Metabolic processes are essential as they govern both the breakdown of nutrients to obtain usable energy and the construction of new molecules that cells require to function.