Final answer:
ATP breakdown provides energy for the mechanical work of muscle contraction and the active transport of ions such as those in the sodium-potassium pump.
Step-by-step explanation:
When ATP is broken down, the cell is provided with a quick burst of energy required for many cellular activities.
Two primary examples include the mechanical work of muscle contraction, where the energy from ATP is used to move the contractile muscle proteins, and the active transport work, like that of the sodium-potassium pump in the cell membranes, in which ATP alters the protein structure to change its affinity for sodium and potassium ions, effectively pumping them against their electrochemical gradients.