Two similar animal cells are placed in two different solutions: Cell X is placed in pure water. Cell Y is placed in a concentrated salt solution. Cells are observed after some time. Cell X swells, and Cell Y shrinks. Which statement provides the correct explanation for the above observations?
Explanation
Option (iii) is correct because the cell membrane is selectively permeable; it allows water to move in and out of the cell but not salt or sugar molecules. When Cell X is placed in pure water (a hypotonic solution), water moves into the cell, causing it to swell. When Cell Y is placed in a concentrated salt solution (a hypertonic solution), water moves out of the cell, causing it to shrink. Osmosis is the movement of water across a selectively permeable membrane, not the movement of solute, which makes options (i), (ii), and (iv) incorrect.