ANATOMY

Detailed explanation-1: -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.

Detailed explanation-2: -Facilitated diffusion is a type of passive transport. Even though facilitated diffusion involves transport proteins, it is still passive transport because the solute is moving down the concentration gradient. Small nonpolar molecules can easily diffuse across the cell membrane.

Detailed explanation-3: -Channel proteins span the membrane and make hydrophilic tunnels across it, allowing their target molecules to pass through by diffusion.

Detailed explanation-4: -Facilitated diffusion uses integral membrane proteins to move polar or charged substances across the hydrophobic regions of the membrane. Channel proteins can aid in the facilitated diffusion of substances by forming a hydrophilic passage through the plasma membrane through which polar and charged substances can pass.