Here's why:
* The cell membrane acts as a barrier: It separates the inside of the cell (cytoplasm) from the outside environment.
* Selectively permeable: The cell membrane is selectively permeable, meaning it controls which substances can enter and leave the cell.
* Transport mechanisms: The membrane uses various transport mechanisms to move substances, including:
* Passive transport: Movement of substances across the membrane without energy expenditure (e.g., diffusion, osmosis).
* Active transport: Movement of substances across the membrane requiring energy expenditure (e.g., pumps, endocytosis, exocytosis).
The cell membrane's ability to control the passage of substances is crucial for maintaining the cell's internal environment and carrying out essential functions.
