Question

conducts the experiment to the presence of starch in the leaf.​

Answer 1

ANSWER

A positive test for starch in a leaf provides evidence that photosynthesis has occurred by the formation of violet black colour in the presence of iodine solution.

Collection of green leaf and exposed them to sunlight for a few hours

Heat the 250cm  

3

water until it boils. Keep the water at boiling point.

Place the leaf in the boiling water with the help of forceps and boil for 2 minutes.

Turn off the Bunsen Burner. (If you are using a heat source without a naked flame - electric water bath or hot plate - this step is unnecessary.)

Place the boiled leaf in a boiling tube containing 90% ethanol.

Place the boiling tube in hot water and boil for 10 minutes or until the leaf decolorizes. (It may be necessary to replace the ethanol.)

Gently remove the leaf and wash with a fine trickle of cold tap water.

Spread the leaf evenly on a white tile.

Add a few drops of iodine/potassium iodide solution to the leaf and note any observations.

This is from my book hope it helps.

Answer 2

pluck a leaf from a plant which has been exposed to sunlight.

boil it in water for five minute and place it in another beaker containing alcohol. now, boil the leaf in alcohol.it will dissolve the chlorophyll and will be come colourless.

then, wash the leaf with water to remove the alcohol.

now, place the leaf on a white paper and pour a few drops of iodine solution on it. what do you observe?

you will observe that the part of leaf becomes blue- black. the blue-black colour shows the presence of starch in a leaf.

this experiment soch the presence of starch in leaf.