Ontario Grade 9 Science Class Practice Exam 2025 - Free Grade 9 Science Practice Questions and Study Guide

ATP, or adenosine triphosphate, plays a crucial role in cellular processes primarily as a source of energy. Cells require energy to perform various functions, such as muscle contractions, active transport of molecules across membranes, and biochemical reactions. ATP serves as the energy currency of the cell, providing the necessary energy by releasing one of its three phosphate groups through hydrolysis, which converts ATP into ADP (adenosine diphosphate) and inorganic phosphate. The energy released during this reaction is utilized for these vital cellular activities, making ATP central to the metabolism of all living organisms.

While ATP participates in cellular respiration and is involved in energy transfer reactions, its primary designation is as the energy source for cellular processes. In contrast, other options focus on functions that are not central to ATP's role, such as the storage of genetic information or being a building block of proteins, both of which pertain to different biomolecules entirely.