1. Muscle Contraction: The process of muscle contraction, which allows us to move, requires ATP (adenosine triphosphate), the energy currency of cells. ATP is used to power the sliding filament mechanism within muscle fibers.

2. Active Transport: Moving molecules across cell membranes against their concentration gradient (from an area of low concentration to high concentration) requires energy. This is essential for maintaining the correct balance of ions and nutrients within cells.

3. Protein Synthesis: The process of building proteins from amino acids is energy-intensive. It involves the formation of peptide bonds, which requires energy supplied by ATP.