Take four peeled potato halves and scoos 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 the boiled potato cup D.
Keep these 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.Â
Ans: Water gathers in the hollowed portion of cups B and C because of osmosis. In cup B, where sugar is added, water molecules move from the area of higher concentration (outside the potato cup) to the area of lower concentration (inside the cup) to dilute the sugar solution. Similarly, in cup C, where salt is added, water molecules move from the area of higher concentration (outside the potato cup) to the area of lower concentration (inside the cup) to dilute the salt solution.
(ii) Why is potato A necessary for this experiment?
Ans: Potato A, which is kept empty, serves as a control in the experiment. It helps us understand the changes observed in the other potato cups (B, C, and D). By comparing the results of potato A with those of the other cups, we can determine the effects of adding sugar, salt, or boiling the potato on water movement.
(iii) Explain why water does not gather in the hollowed out portions of A and D.
Ans: Water does not gather in the hollowed-out portions of cups A and D because there is no solute added to create a concentration gradient. In cup A, which is empty, there is no solute to cause osmosis. In cup D, where sugar is added to the boiled potato, the boiling process likely damages the cell membranes, preventing osmosis from occurring effectively. Therefore, water does not accumulate in the hollowed-out portions of cups A and D.
