Facilitated diffusion is a type of passive transport that allows substances to cross cell membranes with the help of special transport proteins.
The movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.
The movement of biochemicals and other atomic or molecular substances across cell membranes without need of energy input.
Proteins that serve in biological transport. They are vital for all organisms as they allow many essential solutes to move in and out cells.