The movement of ions and other atomic or molecular substances across cell membranes without the need for energy input is known as

passive transport

Explanation:

The movement of ions across a cellular membrane without the need for energy input is known as passive transport. Diffusion is the passive movement of molecules from an area of high concentration to low concentration. Voltage describes the difference in electrical potential between two separate points, and isotonic movement describes the activity of a system at equilibrium.

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