GENERAL HISTOLOGY

Detailed explanation-1: -In cells, some molecules can move down their concentration gradients by crossing the lipid portion of the membrane directly, while others must pass through membrane proteins in a process called facilitated diffusion.

Detailed explanation-2: -Diffusion is the movement of particles down their gradient.

Detailed explanation-3: -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-4: -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-5: -In facilitated transport, membrane proteins assist the diffusion of materials through the cell membrane. The protein binds the molecule being transported on the surface of the membrane, then passes it to interior proteins that typically form a channel or pore in the membrane.