The barrier between the protoplasin and the outer environment in a plant cell is :

Options

A. Nuclear membrane
B. Plasma membrane
C. Tonoplast
D. Cell wall

Answer

**Step-by-Step Solution:**

1. **Understanding Cell Structure**: In a plant cell, there are two main layers that can be considered as barriers: the cell wall and the plasma membrane.

2. **Identifying the Cell Wall**: The cell wall is the outermost layer of a plant cell. It provides structural support and protection but is not selectively permeable.

3. **Understanding the Plasma Membrane**: The plasma membrane, also known as the cell membrane, is located just inside the cell wall. It is a selectively permeable barrier that regulates the movement of substances in and out of the cell.

4. **Determining the Correct Barrier**: The question specifically asks for the barrier that separates the protoplasm (the living contents of the cell) from the outer environment. The plasma membrane fulfills this role.

5. **Conclusion**: Therefore, the correct answer to the question is the plasma membrane.

**Final Answer**: The barrier between the protoplasm and the outer environment in a plant cell is the plasma membrane.

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