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

What is meant by plasmolysed in cells?

1. When there is a net movement of water into the cell

2. When there is a net movement of water out of the cell

3. When the cell membrane fuses with the cell wall

4. When the cell wall becomes impermeable

The correct answer is: When there is a net movement of water out of the cell

Plasmolysis refers to the process that occurs in plant cells when they lose water, causing the cell membrane to pull away from the rigid cell wall. This process happens when a plant cell is placed in a hypertonic solution, where the concentration of solutes outside the cell is higher than that inside the cell. As a result, water moves out of the cell through osmosis, leading to a net movement of water out of the cell. When this occurs, the vacuole decreases in size, resulting in a loss of turgor pressure, which is the pressure exerted by the fluid inside the vacuole against the cell wall. The cell appears shriveled, and the membrane detaches from the cell wall, highlighting the impact of water movement in osmotic processes. In this case, the terminology accurately reflects the physiological changes that take place at the cellular level, illustrating the importance of water balance in maintaining cell structure and function.