Mineral salts can be absorbed into the roots by diffusion and active transport. Diffusion is the net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout.

Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration—in the direction against some gradient or other obstructing factor (often a concentration gradient).