Simple Diffusion

Question

Simple diffusion
A) does not require energy.
B) utilizes proteins to move molecules across a membrane.
C) requires energy.
D) cannot occur without a membrane present.
E) moves molecules against a concentration gradient.

Accepted Answer

Simple diffusion is a passive process that allows molecules to move down their concentration gradient from an area of high concentration to an area of low concentration. This process does not require energy, making choice A the best answer. Choice B is incorrect because simple diffusion does not involve proteins, and choice C is incorrect because it does not require energy. Choice D is incorrect because simple diffusion can occur through any semi-permeable membrane, not just biological membranes. Finally, choice E is incorrect because simple diffusion occurs down a concentration gradient, not against it.