Osmosis drives water movement based on external sugar concentration

Steps:

• All cells have identical initial cytoplasmic water potential, so internal solute concentration is the same.
• External solutions have decreasing sugar concentrations (10% > 5% > 1%), creating a gradient of water potentials (ψ_{10%} < ψ_{5%} < ψ_{1%}, more negative to less negative).
• In 1% solution (highest ψ outside), water enters the cell, causing turgidity.
• Cell Q appears turgid, matching the hypotonic 1% solution.

Why C is correct:

• Turgid cells result from water influx in hypotonic solutions (external ψ > internal ψ), defining the 1% solution as hypotonic relative to cell cytoplasm.

Why the others are wrong:

• A: Equal concentrations imply isotonic conditions (no net water movement), but cell P likely shows shrinkage, indicating hypertonic external solution.
• B: Flaccid cells indicate isotonic conditions (ψ outside = ψ inside), not hypotonic 1% solution.
• D: Plasmolysis in R shows water efflux, so external ψ is more negative (lower) than internal ψ.

Final answer: C