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Answer:
The movement of molecules across a membrane without the input of energy is known as 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:
got this from somewhere hope it helps. if its wrong im very sorry
Answer:
The primary function of the plasma membrane is to protect the cell from its surroundings