OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What effectively happens to a cell when it becomes plasmolysed?

1. It swells and bursts

2. It loses turgor pressure and becomes limp

3. It becomes more rigid

4. It absorbs more water

The correct answer is: It loses turgor pressure and becomes limp

When a cell becomes plasmolysed, it loses water and, as a result, experiences a decrease in turgor pressure, leading it to become limp. This process typically occurs in plant cells when they are placed in a hypertonic solution, where the concentration of solutes outside the cell is greater than inside. As water moves out of the cell through osmosis to balance the solute concentrations, the vacuole shrinks, pulling the cell membrane away from the cell wall. This loss of pressure is what causes the cell to lose its firmness and rigidity, resulting in a wilted appearance. In contrast, the other outcomes listed are not representative of plasmolysis. Cells do not swell and burst in this situation; rather, they experience a loss of water. Cells also do not become more rigid during plasmolysis, nor do they absorb more water, as these actions are associated with cytolysis or normal turgid cell conditions, not plasmolysis.