The cell contents will shrink away from the cell wall.
Explanation
The movement of water across a semi-permeable membrane is governed by osmosis. The direction of water flow depends on the tonicity of the external solution relative to the cell sap:
- Hypertonic Solution: Higher solute concentration (lower water potential) outside the cell.
- Hypotonic Solution: Lower solute concentration (higher water potential) outside the cell.
- Isotonic Solution: Equal solute concentration on both sides.
Option Analysis
- The cell will swell and eventually burst. is Incorrect: A cell swells when placed in a hypotonic solution because water enters the cell (endosmosis). In plant cells, the rigid cell wall prevents bursting, leading to turgidity.
- The cell will maintain its shape with no net movement of water. is Incorrect: A cell maintains its shape with no net movement of water only when placed in an isotonic solution, where the osmotic pressure inside and outside the cell is in equilibrium.
- The cell contents will shrink away from the cell wall. is Correct: When a plant cell is placed in a hypertonic solution, water moves out of the cell into the external solution (exosmosis). As the central vacuole loses water, the protoplast (cell membrane and internal contents) shrinks and pulls away from the rigid cell wall. This phenomenon is known as plasmolysis.
- The cell wall will dissolve into the solution. is Incorrect: The cell wall is composed of cellulose, a structural polysaccharide that provides rigidity. It does not dissolve merely due to changes in the osmotic concentration of the surrounding solution.
Key Takeaway
Plasmolysis occurs when a plant cell is placed in a hypertonic solution, causing water to leave the cell via exosmosis, resulting in the shrinkage of the protoplast away from the cell wall.