Two similar animal cells are placed in two different solutions: Class 9

Two similar animal cells are placed in two different solutions: Class 9

Question 1.

Two similar animal cells are placed in two different solutions: Class 9

1. Cell X is placed in pure water.
2. 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?

(i) Salt molecules moved into Cell Y, causing it to shrink.

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

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

(iv) Solute movement caused osmosis in both cells.

Answer:

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

Explanation:

1. Pure water is a hypotonic solution relative to Cell X. The cell has a higher solute concentration inside than outside. So water moves into Ceil X by osmosis → Cell X swells.
2. Concentrated salt solution is a hypertonic solution relative to Cell Y. The outside has more solute than inside the cell. So water moves out of Cell Y by osmosis → Cell Y shrinks.
3. The cell membrane is selectively permeable - it allows water to move through, but not large solute molecules like salt.