Question:
Carry out the following osmosis experiment: 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. (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) The cups B and C contains sugar and salt respectively. Their presence make the medium hypertonic to the cells of the potato, which contains more of water. Thus, due to the difference in concentrations in the two regions (that is inside the cells and outside the cells), water is drawn out of the cells into the region where sugar or salt is present, that is in the cup region by osmosis.
ii) Yes, potato A is necessary in the experiment because it serves as a control.
iii) Cup A didnt have anything in it, and therefore there was no question of differential concentrations inside and outside the potato cells. Therefore, there was no movement of water and so cup A didnt have water accumulation.
In case of Cup D, a boiled potato was used. Upon boiling, the cell membrane ruptures and the cell is no longer alive as all its contents are out. Therefore, even when sugar was kept in the cup D, there was no osmosis taking place as the cell membranes had ruptured.
Not what you are looking for? Go ahead and submit the question, we will get back to you.
