Which one of these is not an example using facilitated diffusion? a) aquaporins facilitate the diffusion of water in the kidney tubules of many mammals. b) a carrier protein moves sucrose across the membrane with the concentration gradient. c) using the sodium-potassium pump involves the hydrolysis of atp and the release of na+ to the outside of the cell. d) ca+2 moves from high cytoplasmic concentration to low concentration inside the cell using a membrane-spanning protein.