Question

part a
in comparing simple diffusion to facilitated diffusion, you note that
both require a specific carrier or protein channel
both can move substances up, as well as down, a concentration gradient
both require atp
both require a concentration gradient

Explanation:

Simple and facilitated diffusion are passive transport processes. Simple diffusion occurs directly through the membrane without carriers, while facilitated diffusion uses carriers/ channels. Both move substances down a concentration gradient and do not require ATP. Moving up gradients or needing ATP is active transport. Carriers are only in facilitated diffusion.

Answer:

D. both require a concentration gradient