Question

In a dorsiventral leaf, the cobalt chloride paper placed on the lower side of the leaf turns pink rapidly as compared to that on the upper surface because from the lower side

• A. More $O_2$ is evolved
• B. More $C{O}_2$ is evolved
• C. More $H_{2}O$ is lost
• D. All of the above

Answer 1

The correct option is C More $H_{2}O$ is lost

Cobalt chloride paper test is the hygrometric method to demonstrate transpiration. Dry cobalt chloride is blue, while the moist one is pink. There are more number of stomata present on the lower surface of a dorsiventral leaf leading to more transpiratory loss of water from lower surface as compared to the upper surface. Hence the cobalt chloride paper placed on the lower surface will turn pink rapidly as compared to the cobalt chloride paper kept on the upper surface.