Question

I need a simple definition of osmosis, diffusion, and ion channels, all forms of passive transport.

Answer 1

Osmosis - diffusion of water down a concentration gradient.
Diffusion - the movement of particles from a high concentration region to a low concentration region.
Facilitated diffusion - carry mediated transport for large molecules from high concentration to low concentration through the help of transport proteins.

Ion channel - a protein in the cell membrane that facilitates the diffusion of ions down their electrochemical gradient.