The term that refers to all of the chemical reactions occurring in the body, involving the building up of and breaking down of molecules, is .

The term that refers to all the chemical reactions occurring in the body, involving the building up of and breaking down of molecules, is metabolism.

Metabolism consists of two main processes:

1. Anabolism: This is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy, which typically comes from ATP (adenosine triphosphate).

2. Catabolism: This involves the breakdown of complex molecules into simpler ones, which releases energy stored in the chemical bonds of the molecules.

Together, these processes are crucial for maintaining life, as they provide the necessary energy and materials for the growth, repair, and functioning of cells.