Question

required information
primary and secondary active transport proteins differ in that primary active transport proteins
multiple choice
move both molecules down their gradients, while secondary active transport proteins move both molecules against their gradients
move both molecules down their gradients. while secondary active transport proteins couple the movement of an ion down its gradient with the movement of another molecule against its gradient
move both molecules against their gradients, while secondary active transport proteins move both molecules down their gradients
move both molecules against their gradients, while secondary active transport proteins couple the movement of an ion down its gradient with the movement of another molecule against its gradient

Explanation:

Primary active - transport uses energy (usually ATP hydrolysis) to move molecules against their concentration gradients. Secondary active - transport couples the movement of one ion down its electrochemical gradient to drive the movement of another molecule against its concentration gradient.

Answer:

move both molecules against their gradients, while secondary active transport proteins couple the movement of an ion down its gradient with the movement of another molecule against its gradient