Refer to the following paragraph and accompanying figure to answer the following question(s).
-Under what circumstances does membrane transport require energy?
A) wherever large molecules are moved within a cell
B) whenever a solute is moved against its electrochemical gradient
C) whenever an ion moves through a phospholipid bilayer membrane
D) whenever oxygen moves through a phospholipid bilayer membrane

Question

Refer to the following paragraph and accompanying figure to answer the following question(s). 
-Under what circumstances does membrane transport require energy?
A) wherever large molecules are moved within a cell 
B) whenever a solute is moved against its electrochemical gradient 
C) whenever an ion moves through a phospholipid bilayer membrane 
D) whenever oxygen moves through a phospholipid bilayer membrane

Quizplus · Accepted Answer

Membrane transport requires energy whenever a solute is moved against its electrochemical gradient, which requires energy input from ATP or the energy stored in a gradient. This is shown in the figure where the transport of glucose against its concentration gradient requires energy input from ATP.Choices A, C, and D are not correct because the movement of large molecules within a cell, the movement of an ion through a membrane, or the movement of oxygen through a membrane do not necessarily require energy input as they can occur via passive transport.

Refer to the Following Paragraph and Accompanying Figure to Answer