What are the two main categories of metabolism?

Metabolism is fundamentally divided into two main categories: catabolism and anabolism. Catabolism involves the breakdown of complex molecules into simpler ones, releasing energy that can be used by the organism. This process is essential for generating the energy needed for various cellular functions and for producing smaller molecules that can be utilized in different metabolic pathways.

Anabolism, on the other hand, is the process of building complex molecules from simpler ones, requiring energy input. This is critical for growth, repair, and maintenance of cells, as it allows organisms to synthesize necessary biomolecules such as proteins, nucleic acids, and lipids.

The distinction between catabolism and anabolism provides a comprehensive framework for understanding how organisms manage energy and materials to sustain life. The other categories listed in the choices pertain to different physiological processes or types of dietary habits, but they do not represent the primary functional divisions of metabolism itself.