Which of the following describes metabolism?

• A. Only the breakdown of substances for energy
• B. The sum of all chemical reactions in a body
• C. Only the synthesis of complex molecules
• D. The transfer of energy from one organism to another

Answer: (B)

Metabolism encompasses a broad range of biochemical processes that occur within a living organism. It refers specifically to the sum of all chemical reactions that take place in the body, including both catabolic reactions (which break down molecules to release energy) and anabolic reactions (which build complex molecules from simpler ones). This integrated network of reactions allows cells to maintain homeostasis, grow, reproduce, and respond to their environment.

Choosing the option that describes metabolism as the sum of all chemical reactions is accurate, as it reflects the dynamic and interconnected nature of metabolic processes. This definition highlights that metabolism is not limited to the breakdown of substances for energy or the synthesis of complex molecules, but rather includes all reactions that involve the transformation of energy and matter within the organism.