The difference between simple diffusion and facilitated diffusion is that facilitated diffusion can move materials from a higher to a lower concentration. doesn't require atp. can move materials from a lower to a higher concentration. requires atp. requires transporter proteins.

Requires transporter proteins.

Explanation:

Facilitated diffusion is similar to simple diffusion because both the methods carry molecules from higher to lower concentration. Since the movement is along the concentration gradient there is no requirement of energy or ATP. The difference between them lies in the use of transporter proteins. Polar molecules and large ions are not able to diffuse across the semi permeable membrane despite the concentration gradient because the membrane's hydrophobic nature repels them. Transporter proteins are embedded in the membrane and the molecules can pass through them to other side avoiding the hydrophobic membrane. Hence, facilitated diffusion requires transporter proteins.

"d.) carbon dioxide and hydrogen sulfide"