Question

how to test the presence of starch in leave​

Answer 1

the presence of starch I'm a leaf can be done by following steps

1. take a well potted plant and place it in a dark room for few days so that starch present in it gets used up
2. now place that plant again ik sunlight for few hours and pluck a leaf from it
3. now put the leaf in alcohol solution
4. Now put the alcohol solution in a beaker containing water and boil it over the bunsen burner
5. now put some iodine solution over it and see the blue black coloured leaf
6. this shows the areas containing starch

hope it helps u mate

Answer 2

Put one of the plants in the dark for 24 hours; leave the other one on a windowsill.

After 24 hours, put some ethyl alcohol in a beaker and place that in a saucepan full of water. Heat the pan until the ethyl alcohol begins to boil. Remove from the heat.

Use tweezers to dip each of the leaves in the hot water for 60 seconds. Then place them in the beaker of ethyl alcohol for two minutes or until they turn almost white. Set them each in a shallow dish.

Cover the leaves with some iodine solution and watch.

What Happened:

The hot water kills the leaf and the alcohol breaks down the chlorophyll, taking the green color out of the leaf. When you put iodine on the leaves, one of them will turn blue-black and the other will be a reddish-brown. Iodine is an indicator that turns blue-black in the presence of starch. The leaf that was in the light turns blue-black, which demonstrates that the leaf has been performing photosynthesis and producing starch.