Activity to show that starch is formed in leaves
Answers
Explanation:
use iodine solution to checck starch formation.in the presence of starch the leaf convert into brown colour when it contact with iodine solution
Answer:
What You Need:
Two plants
Beaker or glass jar
Saucepan on the stove
Ethyl alcohol
Iodine solution
Tweezers
Test for starch in plants:
Place one of the plants in a dark room for 24 hours; place the other one on a sunny windowsill.
Wait 24 hours.
Fill the beaker or jar with ethyl alcohol.
Place the beaker or jar in a saucepan full of water.
Heat the pan until the ethyl alcohol begins to boil.
Remove from the heat.
Dip each of the leaves in the hot water for 60 seconds, using tweezers.
Drop the leaves in the beaker or jar 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 colour 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.
Try the test again with a variegated leaf (one with both green and white) that has been in the sunlight. A leaf needs chlorophyll to perform photosynthesis — based on that information, where on the variegated leaf do you think you would find starch? The stains would only be seen n the areas where the green colour was present