Question

write an experiment to show that light is necessary for photosynthesis​

Answer 1

Answer: Experiment to prove that sunlight is essential for photosynthesis:

PROCEDURE:

Step 1: Keep the plant in a dark room:

Keep a healthy green plant in a dark room for 24-48 hours. This is done to make sure that the plant utilizes all the stored food and the leaves become devoid of any starch.

Step 2: Cover a particular part of any leaf:

Cover a part of any leaf of this plant on both the sides with a piece of black paper firmly fixed to the leaf blade.

Step 3: Expose the plant to sunlight:

Now the plant is exposed to bright sunlight with the specific part of the leaf staying covered.

Step 4: Decolorize the leaf:

After few hours, remove the leaf and decolorize it in boiling water, using alcohol.

Step 5: Add iodine solution:

This is done to test the presence of starch in the leaf.

OBSERVATION:

We will observe that the portion of the leaf that was covered with the black paper did not show any presence of starch.

INFERENCE:

The food that is prepared by plants by the process of photosynthesis is stored in the form of starch.

This starch changes into black-blue color in presence of Iodine solution.

Only those parts of the leaf changed color that were exposed to sunlight because they could photosynthesize.

And the parts that were covered didn't change any color because no photosynthesis occurred in those parts and thus starch was absent.