Testing leaves for starch
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.
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
- Test tube
- Boiling water
- White tile
- Iodine solution
- Safety Goggles
- Bunsen burner
- safety mat
- glass rod
- Wear safety goggles
- Keep ethanol away from Bunsen burner; ethanol is flammable
- Tie hair back
- Tuck ties, files and loose material away
- Keep all bags out of the way to avoid tripping up.
- Set up the equipment.After follow the steps below.
- Place a beaker of hot water in the hot water bath. When the water has boiled add the leaf that had been in light.
- 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).
- Take out the leaf using the forceps.
- Put the leaf in a boiling tube and cover with ethanol.
- Put the tube of ethanol plus leaf into the beaker of hot water WITHOUT the bunsen burner on as ethanol is highly flammable.
- Dip the leaf back into the hot water, using the forceps.This is done to get the ethanol off the leaf.
- Spread the leaf out on the tile using the glass rod. Add about five drops of iodine solution on to the leaf and observe.
- Carefully draw a diagram of the leaf marking any areas that have stained black.
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.