Final answer:
The selectively permeable plasma membrane regulates the movement of substances in and out of the cell, maintaining the internal environment of the cell.
Step-by-step explanation:
The function of a cell's selectively permeable plasma membrane is to regulate the movement of substances in and out of the cell. It allows certain molecules to pass through while blocking others.
For example, small molecules like oxygen and carbon dioxide can diffuse freely across the membrane, while larger molecules like proteins and sugars require specific transport proteins to facilitate their movement.
This selective permeability helps maintain the internal environment of the cell, allowing it to control the uptake of nutrients and elimination of waste products.
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