What happens to a cell if it takes in too much water?

• A. The cell bursts
• B. The cell shrivels
• C. The cell remains the same
• D. The cell divides rapidly

Answer: (A)

Osmosis drives water across a membrane from a region of lower solute concentration to higher solute concentration inside the cell. When the external solution is hypotonic relative to the cell’s interior, water enters the cell. Without a rigid cell wall to limit expansion, the cell swells until its membrane can no longer contain it and it bursts (lyses). In contrast, plant cells have strong cell walls that prevent bursting; they become turgid as water enters. If water leaves the cell, it shrinks; in an isotonic environment there’s little net water movement and the cell stays about the same size; rapid division isn’t a direct consequence of water uptake. So, taking in too much water most commonly causes bursting in cells without a cell wall.