Final answer:
Cell membranes, like a club, are selectively permeable and control the passage of substances in and out of the cell.
Step-by-step explanation:
Cell membranes, like a club, are selectively permeable. This means they control the passage of substances in and out of the cell, just like a bouncer at a club who decides who can enter and who cannot. They have a phospholipid bilayer that allows only certain molecules to pass through, based on factors like size and charge.
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