Question

In a dorsiventral leaf, the rate of transpiration is unequal. Do you agree? Name the apparatus used for comparing the rate of transpiration from both surfaces of such a leaf.

Answer 1

Transpiration:

The process of loss of water in the form of vapour from the aerial parts of the plants is called transpiration.

Dorsiventral leaf:

1. The dorsiventral leaves are found in dicot plants which have two surfaces that differ in appearance and structure.
2. Even the number of stomata varies on both surfaces.
3. On the upper (dorsal) surface of the leaf, the number of stomata is less as compared to the lower (ventral) surface.

Hence, the rate of transpiration is more at the lower surface as compared to the upper surface.

Cobalt paper:

1. In a bell jar, cobalt paper is tied on both the surfaces of the leaf, and the pot is enclosed within a polythene bag.
2. It is observed that condensation is seen and the blue cobalt paper is turned to pink.
3. The time taken by the upper surface of the leaf to change the color is more than the lower surface.

Dry cobalt paper is used for comparing the rate of transpiration from both surfaces of such a leaf.