Final answer:
The cell membrane determines what can go in and out of the cell and helps hydrophilic molecules cross into the cell.
Step-by-step explanation:
The role of the cell membrane in a cell is to determine what can go in and out of the cell. It acts as a selective barrier and allows only certain substances to pass through while preventing others. The cell membrane is made up of a phospholipid bilayer with embedded proteins that help facilitate the transport of molecules in and out of the cell. For example, hydrophilic molecules (water-soluble) can cross the cell membrane through protein channels like aquaporins.
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