The movement of materials into cells is referred to as active transport and passive transport, depending on whether energy is required.
Passive transport occurs when substances move across the cell membrane without the use of energy. This process relies on concentration gradients, meaning materials flow from areas of higher concentration to areas of lower concentration. Examples include diffusion and osmosis.
On the other hand, active transport requires energy, usually in the form of ATP, to move substances against their concentration gradient—from low concentration to high concentration. This is essential for maintaining the necessary concentrations of ions and other substances inside the cell.
In summary, both active and passive transport are crucial for the movement of materials into cells, allowing them to function properly and maintain homeostasis.