Why is the plasma membrane called a selectively permeable membrane

Explanation

**Step-by-Step Solution:**

1. **Definition of Plasma Membrane**: The plasma membrane, also known as the cell membrane, is a biological membrane that separates and protects the interior of the cell from the external environment.

2. **Function of the Plasma Membrane**: The primary function of the plasma membrane is to control the movement of substances in and out of the cell. This is crucial for maintaining the cell's internal environment and overall homeostasis.

3. **Selectively Permeable Nature**: The term "selectively permeable" refers to the ability of the plasma membrane to allow certain molecules to pass through while restricting others. This means that not all substances can freely enter or exit the cell.

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