Which of the Following Membrane-Crossing Mechanisms Requires Energy

Question

Which of the following membrane-crossing mechanisms requires energy?  
A) Active transport
B) Facilitated diffusion
C) Simple diffusion
D) Passive transport
E) Turgor

Accepted Answer

Active transport requires energy to move molecules against their concentration gradient, while facilitated diffusion and simple diffusion move molecules down their concentration gradient without the need for energy. Passive transport is a general term that includes both facilitated and simple diffusion. Turgor refers to the pressure exerted by water inside plant cells and is not a membrane-crossing mechanism.