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| 1. |
Megha wanted to test the presence of starch in leaves. She performed the following steps: |
| Answer» 1 HEAT a plant leaf in boiling water for 30 seconds (this kills the leaf, stopping any chemical REACTIONS)2 add the leaf to boiling ethanol in a water bath for a few minutes (the boiling ethanol dissolves the chlorophyll and removes the green COLOUR from the leaf - it turns WHITE so it is easy to see the change in colour)3 wash with water to rehydrate and soften the leaf and spread onto a white tile4 add iodine solution from a dropping pipetteAfter a few minutes, the parts of the leaf that contain starch turn the iodine from brown to blue/black. | |