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

What happens when the water potential inside the cell is higher than that of the tissue fluid?

1. Water moves into the cell

2. The cell remains the same size

3. Water moves out of the cell

4. The cell bursts due to overhydration

The correct answer is: Water moves out of the cell

When the water potential inside the cell is higher than that of the tissue fluid, it means that the concentration of solutes is lower inside the cell compared to the surrounding fluid. As a result, water moves out of the cell to reach equilibrium, where the water potential becomes equal on both sides of the cell membrane. This movement occurs through osmosis, where water molecules travel from an area of higher water potential (inside the cell) to an area of lower water potential (the tissue fluid) to balance the concentrations. The other options describe scenarios that do not align with the principles of osmosis in this context. A situation where the cell remains the same size would occur if there is an equal water potential inside the cell and outside. Water moving into the cell would happen if the water potential in the tissue fluid is higher than inside the cell, resulting in a net movement of water into the cell. The cell bursting due to overhydration is a possible outcome if the water potential were significantly different for an extended period, but under the described circumstances, the cell is more likely to lose water rather than gain it, making it unlikely to burst.