Question

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?

Options

• Salt molecules moved into Cell Y, causing it to shrink.

• Water moved into Cell X and more water moved out of Cell Y than the salt solution entered in it.

• Water moved into Cell X and moved out of Cell Y through the cell membrane.

• Solute movement caused osmosis in both cells.

Answer 1

Water moved into Cell X and moved out of Cell Y through the cell membrane.

Explanation:

Cell X is dipped in pure water, which is a diluted (hypotonic) solution. Water enters the cell through osmosis from a higher water concentration (outside) to a lower water concentration (inside), causing the cell to swell. Cell Y is dissolved in a concentrated salt solution, known as a hypertonic solution. Osmosis removes water from the cell, causing it to shrink. The cell membrane is selectively permeable, allowing only water and not salt to pass through. This is why the choices involving the movement of salt molecules (i, ii) and solute mobility (iv) are incorrect.