At fully turgid stage the cell wall prevents the protoplast from increasing in size and exerts a pressure called

Options

A. Wall pressure
B. Turgor pressure
C. Osmotic pressure
D. Suction pressure

Answer

### Step-by-Step Solution:

1. **Understanding the Context**: The question refers to the condition of a plant cell when it is fully turgid. Turgidity occurs when a plant cell is filled with water, causing the protoplast (the living part of the cell) to press against the cell wall.

2. **Role of the Cell Wall**: At the fully turgid stage, the cell wall plays a crucial role. It prevents the protoplast from expanding further, which is essential for maintaining the structural integrity of the plant cell.

3. **Definition of Wall Pressure**: The pressure exerted by the cell wall against the protoplast when it is fully turgid is known as **wall pressure**. This pressure is a result of the cell wall pushing back against the protoplast, preventing it from increasing in size.

4. **Comparison with Turgor Pressure**: It is important to differentiate wall pressure from turgor pressure. Turgor pressure is the pressure exerted by the protoplast against the cell wall. In contrast, wall pressure is the opposing force exerted by the cell wall on the protoplast.

5. **Conclusion**: Therefore, when a cell is fully turgid, the pressure exerted by the cell wall that prevents the protoplast from increasing in size is called **wall pressure**.

### Final Answer:
The pressure exerted by the cell wall at the fully turgid stage is called **wall pressure**.

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