Question

A layer of glycerine was applied on upper surface of a freshwater floating plant that had been kept in the dark for 24 hours. The plant was left undisturbed in bright light. After three hours test for starch carried out on the leaves produced a brown colour of iodine solution. Account for the observation.

Answer 1

The leaf had stomata only on the upper surface; which were blocked by glycerine cutting supply of carbon(IV) oxide; no photosynthesis takes place hence absence of starch;