Flexi Says: Ions in a cell can be transported through passive transport and active transport. Passive transport includes facilitated diffusion that does not require energy. In facilitated diffusion, ions are diffused in the plasma membrane through transport proteins i.e. channel, gated and carrier proteins. In this, some ion channels are always open, others are "gated" and can be opened or closed. The channels are passive and do not tap the cell’s energy to operate. In contrast to facilitated diffusion which does not require energy and carries molecules or ions down a concentration gradient, active transport pumps molecules and ions against a concentration gradient. This process uses the energy of ATP.