Question

Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,

(a) keep cup A empty

(b) put one teaspoon sugar in cup B

(c) put one teaspoon salt in cup C

(d) put one teaspoon sugar in boiled potato cup D.

Keep this setup for two hours. Then observe the four potato cups and answer the following :

(i) Explain why water gathers in the hollowed portion of B and C?

(ii) Why is potato A necessary for this experiment?

(iii) Explain why water does not gather in the hollowed out portions of A and D.

​

Answer 1

Answer:

Sugar and salt solutions both are hypertonic which causes exosmosis and thus, water moves from the cell of lower solute concentration to the outside of the cell of higher solute concentration through the semipermeable membrane of potato and gathered in the hollowed portion and potato lining will shrink. But on boiling potato has lost its semipermeable membrane and thus it will not show any changes.  

Therefore, one control without water is necessary to show that only osmosis is involved in these changes.