Answer the following question given this paragraph: 

What happens if a substance needs assistance to move across or through the plasma membrane? Facilitated diffusion is the diffusion of solutes through transport proteins in the plasma membrane. 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.


Q: What do you call the diffusion of solutes through transport proteins in the plasma membrane?


A:
facilitated diffusion