Final answer:
A membrane is a thin layer of tissue that covers a structure or cavity. It acts as a protective barrier and regulates the movement of substances in and out of the structure.
Step-by-step explanation:
A membrane is a thin layer of tissue that covers a structure or cavity. It acts as a protective barrier and regulates the movement of substances in and out of the structure. For example, the cell membrane surrounds the cell and controls the transportation of molecules.
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