What process involves the movement of materials through a cell membrane using energy?

Active transport is the process that involves the movement of materials through a cell membrane using energy. This energy, often derived from ATP, is required because active transport is employed to move substances against their concentration gradient—meaning from an area of lower concentration to an area of higher concentration. This is crucial for maintaining cellular homeostasis, as cells need to regulate the internal concentrations of various ions and molecules, such as sodium, potassium, and calcium, to function properly.

The distinction between active transport and other processes is important: passive transport, diffusion, and facilitated diffusion do not require energy input. In passive transport, materials move along their concentration gradient without the need for energy, which is not the case in active transport. Understanding these processes and their energy requirements is essential for comprehending how cells maintain their internal environments and react to external changes.