Take a healthy potted plant with elongated leaves. Select a leaf and insert about one half of this leaf in a test tube containing KOH and make it air tight. Place the set-up in sun for two hours. Take out the leaf from the test tube and dip it in boiling water for a few minutes. Put this leaf in a beaker with alcohol and boil it in a water bath. Wash the leaf with water and then dip the leaf in iodine solution for a few minutes. The portion of the leaf dipped in KOH solution will not show any change when dipped in iodine solution. (i) The function of KOH taken in the test tube is to absorb (a) Released water vapours (b) Released CO2 (c) Released O2 (d) Chlorophyll. (ii) On the basis of this activity, we may conclude that the factor for photosynthesis is (a) Carbon dioxide (b) Oxygen (c) Chlorophyll (d) Water vapour. (iii) The event that does not occur in photosynthesis is (a) Absorption of light energy by chlorophyll (b) Reduction of carbon dioxide to carbohydrates (c) Oxidation of carbon to carbon dioxide (d) Conversion of light energy to chemical energy. (iv) Iodine solution gives blue-black colour with (a) Starch (b) Proteins (c) Glucose (d) Fats.