Final answer:
Metabolism is the sum of all energy-requiring and energy-consuming processes of the body, including both catabolic and anabolic reactions, which break down and build up molecules, respectively.
Step-by-step explanation:
Metabolism is best described as the sum of all energy-requiring and energy-consuming processes in the body. These metabolic processes are a combination of catabolic and anabolic reactions. Catabolic reactions break down molecules to release energy, like when the body breaks down food. On the other hand, anabolic reactions use that energy to build larger molecules from smaller ones, such as the synthesis of proteins from amino acids. Factors that contribute to an individual's metabolism include lean muscle mass, the quality of food consumed, and physical demands placed on the body.
Metabolic rate is a measure of how much energy the body uses to maintain vital functions. To sustain life, an organism must consume a sufficient amount of food to support its metabolic rate. Understanding metabolism is crucial as it represents how an organism manages its material and energy resources, impacting growth and homeostasis.