AP BIOLOGY

Detailed explanation-1: -Osmosis. Osmosis is the diffusion of water through a semipermeable membrane according to the concentration gradient of water across the membrane.

Detailed explanation-2: -Diffusion is a random movement of molecules down the pathway called the concentration gradient. Molecules are said to move down the concentration gradient because they move from a region of higher concentration to a region of lower concentration.

Detailed explanation-3: -In facilitated diffusion, substances move into or out of cells down their concentration gradient through protein channels in the cell membrane. Simple diffusion and facilitated diffusion are similar in that both involve movement down the concentration gradient.