IB Biology Practice Exam

Hypotonic solutions are characterized by having lower osmolarity compared to the cell cytoplasm. This means that the concentration of solutes in the hypotonic solution is less than that inside the cell. When a cell is immersed in a hypotonic solution, water will move into the cell by osmosis in an attempt to equalize the solute concentration across the cell membrane. This influx of water can cause the cell to swell and potentially burst if too much water enters.

In contrast, solutions with higher osmolarity than the cytoplasm would be hypertonic, leading to water leaving the cell and causing it to shrink. Solutions with the same osmolarity would be isotonic, resulting in no net movement of water, maintaining the cell's size and shape. Additionally, equilibrium of solute concentration indicates an equal distribution of solutes on both sides of the membrane, which does not align with the definition of a hypotonic solution.

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