Sunlight necessary for photosynthesis

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  To show that sunlight is necessary                     for photosynthesis.

       Let's we do a experiment. 

We will now perform a activity that show  sunlight is  necessary for photosynthesis. By the end of this activity we will show that leaves finally make starch as food by photosynthesis. 

•  Take a potted plant with green leaves. 

•  Place it in a dark room for 3 days, so that all the starch is used up by the leaves. 

•  Cover a part of leaf of the plant with aluminum foil or black paper. 


•  Now keep the plant in sunlight for about six hours. 

•  Pluck the partially covered leaf from the plant and remove the foil. 

•  Boil the leaf in water to denature the enzymes. Now boil the leaf in water until flaccid and then imersed it in warm 90% alcohol solution until decolourised. Thus leaf will become colurless.              


•  Place this decolourised leaf in a petri dish and add iodine solution over it with the help of a droper. 

•  Observe the change in colour of the leaf. 


•  You will observe that only the areas which had received sunlight turn blue with iodine. 

 Que.  If sunlight is dim what is the effects  on rate of photosynthesis. 

                   THANKS

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