School Science/Testing leaves for starch

Testing leaves for starch

Introduction
In a food chain, plants are usually the producers, which means they can make food by themselves. They make food by carrying out photosynthesis, then storing the food made in the form of starch.

Aim
The aim of the experiment is to compare a covered part of a leaf to an uncovered part of a leaf to see whether plants produce starch

Equipment

 * Beaker
 * Test tube
 * Water 200 ml
 * Boiling water any amount that doesn't exceed 600 ml
 * Ethanol 5 ml
 * White tile
 * Iodine solution 3 drops
 * Safety Goggles
 * Leaves
 * Bunsen burner
 * Apron
 * safety mat
 * gauze
 * tripod
 * forceps or tweezers
 * glass rod

Safety precautions

 * Wear safety goggles
 * Keep ethanol away from Bunsen burner; ethanol is flammable
 * Tie the hair back
 * Tuck ties, files and loose material away
 * Keep all bags out of the way to avoid tripping up.
 * Make sure you are not wearing tight clothes
 * Use the forceps to place the leaf in the boiling water

Method

 * 1) Arrange the apparatus as shown in the figure.
 * 2) Place a beaker of hot water in the hot water bath. When the water has boiled add the leaf that had been in light.
 * 3) Wait 3 minutes for the leaf to boil (this is to get rid of the waterproof layer and break the open cells and make it soft).
 * 4) Take out the leaf using the forceps.
 * 5) soak it in the ethanol and the water.
 * 6) Put the leaf in a boiling tube and cover with ethanol.
 * 7) Put the tube of ethanol plus leaf into the beaker of hot water WITHOUT the bunsen burner on as ethanol is highly flammable.
 * 8) Dip the leaf back into the hot water, using the forceps.This is done to get the ethanol off the leaf.
 * 9) Spread the leaf out on the tile using the glass rod. Add about five drops of iodine solution on to the leaf and observe.
 * 10) Carefully draw a diagram of the leaf marking any areas that have stained black.

Results
From this experiment, you will discover that leaves contain starch in the black parts of the leaf. But originally where the green parts of the leaf were present starch is available in lesser quantity.

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