The cell process that provides an organism with energy by breaking down nutrients is cellular respiration.

Here's a breakdown:

* Cellular respiration is a series of metabolic reactions that occur in the cells of organisms to convert chemical energy from nutrient molecules (like glucose) into a form that the cell can use, primarily ATP (adenosine triphosphate).

* This process involves three main stages: glycolysis, the Krebs cycle, and the electron transport chain.

Let me know if you'd like a more detailed explanation of each stage!