Here's why:

* ATP (adenosine triphosphate) is the primary energy currency of cells. It's like the "fuel" that powers all cellular processes.

* Cellular processes that require ATP include:

* Muscle contraction: Moving your body requires energy from ATP.

* Active transport: Moving molecules across cell membranes against their concentration gradients needs ATP.

* Protein synthesis: Building proteins, essential for all cell functions, uses ATP.

* Cell signaling: Communicating between cells and within cells requires ATP.

* Cell division: Creating new cells requires energy from ATP.

* Nerve impulse transmission: Sending signals through your nervous system uses ATP.

* Maintaining cell structure: Keeping the cell's shape and integrity requires energy from ATP.

Essentially, any process that requires energy within a cell will use ATP.