question_answer 9)

Carry out the following osmosis experiment: Take four peeled potato halves and scoop 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. (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:

(i) Water gathers in B and C because in both the situations there is difference in the concentration of water in the through and water in the cup (Potato). Hence endosmosis takes place as the potato cells-act as a semipermeable membrane. (ii) Potato cup A is necessary in the experiment as a ‘control’ for providing comparison with situations created in potato cups B, C and D. It indicates that the potato cavity alone does not induce movement of water. (iii) Water does not gather in hollowed out portions of A and D as cup in A does not have change in concentration of water flow and for osmosis, concentration should be higher than other. In cup D cells are dead, hence semi premeable membrane is not existing for How of water and no osmosis takes place.