Answer:
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Experiment steps: 1 Mark each
Inference: 1 Mark
Chlorophyll is extremely important to perform photosynthesis since it is the compound responsible for harnessing sun's energy.
To prove the importance of photosynthesis, the following steps are performed in a sequential order.
Step-1:Take a beaker with boiling water and drop a croton leaf into it. Let it boil for 2 minutes(A croton leaf is a variegated leaf with white and green patches)
Step-2:Take the leaf out of the beaker and place it in a test tube with alcohol. Place this test tube in a hot water bath for 10 minutes. Alcohol decolourises the leaf by removing chlorophyll from it by the process of bleaching.
Step-3:Remove the leaf from alcohol and wash it with warm water. Place it on a tile for further test.
Step-4:Add 2 drops of iodine onto the leaf. The portions which were green i.e. contained chlorophyll turn into bluish-black colourindicating a positive test for starch. The portions which did not contain chlorophyll and did not participate in photosynthesis turns brown because of the iodine solution indicating a negative test for starch.
This experiment proves that food, or starch, is made only in the places of the leaves which are green, or in other words, have chlorophyll in them. So we can conclude that chlorophyll is necessary to performphotosynthesis.