Page 69 - Viva ICSE Science 4 : E-book

ACTIVITY TIME

Iodine test to detect the presence of starch in leaves

Aim:
To detect the presence of starch in leaves using iodine solution

You Need:

A potted plant, a beaker, water, alcohol, iodine solution, forceps, test tube, dropper

What to Do:

• Take a healthy potted plant and keep it in sunlight for 2 days. Water the plant regularly.
• Pluck a leaf from the plant that has been exposed to sunlight. Go to the laboratory with
your teacher to observe the experiment carefully.

• Fill half of the beaker with water and place it on the fl ame to boil it.
• Place the leaf in boiling water using forceps and allow it to boil for 2 minutes.

• Remove the boiled leaf using forceps and place it in a test tube containing alcohol.
• Place the test tube in boiling water for 10 minutes until the leaf becomes colourless.

• Now remove the leaf gently and wash it with cold water.
• Place the leaf on a white tile and add a few drops of iodine solution on it using the
dropper.

Observation:
You will observe that the leaf turns blue-black on adding iodine solution indicating
the presence of starch in it.

Result:

This shows the presence of starch in leaves.

55