Social Sciences, asked by tanu664250, 1 year ago

test for leaf starch

Answers

Answered by RAMAKRISHNA11
2

Explanation:

The presence of starch in leaves can be tested by the Iodine test. When we remove chlorophyll from the leaf by boiling it in alcohol and then put two drops of iodine solution, it is colour change to blue indicates the presence of starch

apparatus:

bunsen burner, tripod stand, wire gauze(OR 90oC electric water bath OR hot plate)

250 cm3 beaker

boiling tube

anti- bumping granules

forceps

test tube holder

white tile

leaf to be tested (hibiscus leaves are excellent)

90% ethanol

iodine/potassium iodide solution.

procedure:

Remove a green leaf from a plant that has been exposed to sunlight for a few hours

Half-fill a 250cm3 beaker with water. Heat the water until it boils. Keep the water at boiling point.

Use the forceps to place the leaf in the boiling water. 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 decolourizes. ( 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.

Observations:

The leaf was flaccid (soft) after being boiled in water

The ethanol changed from colorless to green

The leaf was brittle after being boiled in ethanol

The leaf become flaccid once more after being rinsed in cold water

After iodine solution was added...

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