Why chlorophyll is essential for photosynthesis

A potted plant with variegated leaves like money plant was taken for the activity. The plant was kept in a dark room for three days so that all the starch gets used up. Then the plant was kept in sunlight for about six hours. A leaf was plucked from the plant and the green areas in it were marked and traced on a sheet of paper. The leaf was dipped in boiling water for a few minutes and after that it was immersed in a beaker containing alcohol. The beaker was placed in a water bath and heated till the alcohol started boiling.

It was observed that the leaf decolourised when it was boiled in alcohol and the solution became green as alcohol removed chlorophyll.
After this, the leaf was dipped in iodine solution for a few minutes and rinsed off.
The blue-black colour appeared only on those parts of the leaf which were green in colour and the variegated parts remained unaffected.
It can be concluded from the above activity that the starch formation takes place only in green parts of the leaf which contain chlorophyll.