The two test tubes in the given figure are kept in a warm dry place. What will you observe after some time?

Options

A. The water level in tube Y will fall down due to evaporation
B. The water level in tube X will fall down due to transpiration,
C. The water level in both the tubes X and Y will remain the same.
D. Both A and B

Answer

B

Explanation

In the given figures, test tubes X and Y contain equal amount of water and a layer of oil is present over the water surface in both the tubes. Test tube X also, contains a plant having its roots in the water. If the two test tubes are kept in a warm dry place, the leaves of plant in tube X will release water through stomata in the form of water vapour in order to cool the plant body in hot weather. This process is called transpiration. As the water escapes from the leaves, roots will pull more water from test tube to compensate for this loss. Hence, the water level will fall down in test tube X. On the other hand, in test tube Y, there is no plant so the possibility of water loss through transpiration is ruled out. Also the process of evaporation cannot take place due to the presence of oil layer on the water surface. Hence, the water level in test tube Y will remain same.