. How would you test the presence of starch in leaves?
Answers
Answer:
Presence of starch in leaves can be tested by iodine test. Iodine turns starch solution into blue-black colour. Pour few drops of dilute iodine solution on the boiled leaf. The leaf becomes blue-black which proves the presence of starch in it.
Answer:
Take a potted plant with variegated leaves – for example, money plant or crotons.
Keep the plant in a dark room for three days so that all the starch gets used up.
Now select a leaf, cover its portion with a black strip paper and keep the plant in sunlight for about six hours.
Pluck a leaf from the plant. Mark the uncovered area in it and trace them on a sheet of paper.
Dip a leaf in boiling water for a few minutes.
After this, immerse it in a beaker containing alcohol.
Carefully place the above beaker in a water-bath and heat till the alcohol begins to boil.
Now dip the leaf in a dilute solution of iodine for a few minutes.
Take out the leaf and rinse off the iodine solution.You observe that the presence of starch in various areas of the leaf which was uncovered.