Final answer:
Cell membranes are selectively permeable, enabling the control of substances entering and exiting the cell. This regulation is essential for maintaining homeostasis and proper cell function.
Step-by-step explanation:
Cell membranes are selectively permeable, which means that they allow certain substances to pass through while blocking others. This is an essential feature of cell membranes as it helps regulate the movement of molecules in and out of the cell. Selective permeability is made possible by the presence of protein channels and transporters in the membrane, which selectively allow specific molecules or ions to cross.
For example, some small molecules like water and oxygen can freely diffuse across the cell membrane through passive transport. On the other hand, larger molecules or charged ions require specialized transport proteins, such as carrier proteins or ion channels, to facilitate their movement.
The selective permeability of cell membranes is crucial for maintaining homeostasis within the cell and allowing it to function properly. By controlling the entry and exit of substances, the cell can regulate its internal environment, prevent the loss of important molecules, and ensure the proper balance of ions and nutrients.
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