Question

List out the materials required and the procedure to be followed to prove that "Carbon dioxide is essential for Photosynthesis".

Answer 1

MATERIALS REQUIRED:

Two potted plants, two bell jars, glass plates, anhydrous potassium hydroxide, iodine, alcohol, dropper, water bath.

PROCEDURE:

• Take two potted plants and keep them in dark for 24 hours so that all the starch in the leaves get used up.
• Keep the potted plants on glass plates and cover them with bell jars.
• Put some anhydrous potassium hydroxide in a petri dish in one of the bell jars.
• Keep the apparatus in sunlight for about 4 hours.
• Now pluck a leaf from both the plants.
• Boil the leaves in alcohol using a water bath.
• Now pour some drops of iodine on the leaves to test for the presence of starch.

RESULTS:

The leaf which turns blue shows the presence of starch as photosynthesis occurred in it whereas the leaf is taken from the bell jar having potassium hydroxide didn't show blue colour because it has no starch as no photosynthesis occurred. This is because potassium hydroxide absorbs carbon dioxide.

This shows that carbon dioxide is essential for photosynthesis.