What does facilitated diffusion across a cell membrane require

Explanation: In facilitated diffusion, molecules diffuse across the plasma membrane with assistance from membrane proteins, such as channels and carriers. A concentration gradient exists for these molecules, so they have the potential to diffuse into or out of, the cell by moving down it.

69 is the correct math for the amino acids

c is the answer to this question. altitude affects the weather because air molecules evaporate.