Chapter 3, Problem 9RAC

Which of these statements about facilitated diffusion is true?
a. In facilitated diffusion, net movement is down the concentration gradient.
b. Facilitated diffusion requires the expenditure of energy.
c. Facilitated diffusion does not require a carrier protein.
d. Facilitated diffusion moves materials through ion pumps.
e. Facilitated diffusion moves materials in vesicles.