Which way of moving molecules across a membrane requires energy?

Active Transport

Explanation:

When energy is needed, the movement is known as active transport. Active transport moves molecules against their concentration gradient, from an area of low concentration to an area of high concentration.

the movement of molecules across a membrane without the input of energy is known as a passive transport. When energy (ATP) is needed, the movement is known as active transport.Active transport moves molecules against their concentration gradient, from an area of low concentration to an area of high concentration.

Explanation:

dynamic equilibrium is the answer.