Osmosis drives water loss from potato cells in hypertonic salt solution

Steps:

• Potato cylinder loses mass after soaking in salt solution, indicating net water outflow from cells.
• Salt solution is hypertonic, with lower water potential than potato cells initially.
• Water moves by osmosis from higher water potential (potato) to lower (solution).
• This outflow causes cell membranes to pull away from walls, resulting in plasmolysis and mass reduction.

Why A is correct:

• Potato cells start with higher water potential than the solution, so water exits via osmosis (defined as diffusion of water across a semi-permeable membrane down a water potential gradient), leading to plasmolysis.

Why the others are wrong:

• B: Higher water potential would cause water entry, making cells turgid and gaining mass, not losing it.
• C: Lower water potential in potato would draw water in, preventing plasmolysis and mass loss.
• D: Lower water potential would promote water uptake, causing turgidity rather than mass loss.

Final answer: A