What term describes all biochemical reactions that occur within an organism, including both anabolic and catabolic processes?

• A. Metabolism
• B. Homeostasis
• C. Respiration
• D. Digestion

Answer: (A)

Metabolism describes all biochemical reactions that occur in an organism. It includes catabolic processes, which break down molecules to release energy, and anabolic processes, which use that energy to build complex molecules. These two types of reactions form the integrated network that powers cellular activities, growth, and maintenance. Enzymes drive these pathways as catalysts, and ATP acts as the energy currency linking energy release to biosynthetic work. In contrast, respiration refers to a specific energy-yielding pathway, digestion is the breakdown of food in the digestive system, and homeostasis is about maintaining stable internal conditions—none of these capture the entire set of metabolic reactions.