In the phase of metabolism called ________, substances such as nutrients are changed into more complex substances and used to build body tissues.

Metabolism

The set of chemical reactions that occur within a living organism to maintain life, involving the breakdown of substances to generate energy and the synthesis of substances necessary for life.

Nutrients

Essential compounds that organisms need to absorb from their surroundings or diet to support growth, reproduction, and health, including vitamins, minerals, proteins, fats, and carbohydrates.