Question

Moll's experiment shows

• A. Relation between transpiration and absorption
• B. Unequal transpiration from two surfaces of leaf
• C. $C{O}_2$ is required for photosynthesis
• D. Chlorophyll is essential for photosynthesis

Answer 1

Answer: (C)

• Moll's half leaf experiment is done for proving that plants can not photosynthesize without carbon dioxide.
• In this experiment, a leaf is placed in a beaker containing water between the two halves of the cork so that one-half lies inside the bottle and the other half outside it with the tip of the leaf/twig dipped in water in the beaker or dish.
• Prepare the bottle by pouring a small amount of caustic potash solution and lay the bottle on its side.
• Seal the mouth of the bottle with the split cork inside which the leaf is lodged.
• Expose the apparatus to sunlight for a few hours, preferably until evening.
• Remove the leaf and decolorize it with alcohol. Test for the presence of starch using iodine solution.
• When tested for starch with the iodine solution, the portion of the leaf outside the bottle turns black, while the portion inside does not indicate the absence of starch because inside the bottle there was limited carbon dioxide which gets over after some time and thus, photosynthesis does not take place but outside the bottle, there was enough carbon dioxide to proceed photosynthesis and thus turns black in the presence of iodine solution.