Necessity of SUNLIGHT for plants || How do plants absorb sunlight??

Experiment to show that sunlight is necessary for photosynthesis.

1. Take a potted plant having green leaves and place it in a dark place for about 3-4
days to destarch its leaves.

2. Take a thin strip of aluminium foil and wrap it on the centre of one leaf on both the
sides so that sunlight may not fall on this covered part of the leaf.

3. The remaining part of the leaf remains uncovered and exposed to sunlight.

4. Now keep this plant in bright sunshine for about 3 - 4 days.

5. Pluck the partially covered leaf from the plant and remove its aluminium foil.

6. Remove its green colour chlorophyll by boiling the leaf in alcohol with the help of water bath.

7. Wash the decolourised leaf with hot water to soften it and remove any chlorophyll which may be stícking to it.

8. Pour iodine solution over the colourless leaf and observe the change in colour of the leaf.

Result:

The middle part of the leaf which was covered with aluminium foil does not turn blue-black on adding iodine solution showing no starch present in this part of leaf. The uncovered part of the leaf which was exposed to sunlight turns blue-black on adding iodine solution showing that starch is present in this part of leaf.

Inference:

Since the part of the leaf which was covered and hidden from sunlight

does not contain starch but the part of the leaf which was exposed to sunlight contains 

starch therefore we can say that sunlight ís necessary for photosynthesis.

Trapping of sunlight by green plants

Light energy from the sun is used to split water molecules in the plants.Green plants trap sunlight with the help chlorophyll present in the chloroplast. chloroplasts are the organelles in the cells of green plants.

The sunlight hits chloroplasts in the plant, causing an enzyme to break apart the water. Water, when broken, makes oxygen, hydrogen and electrons and plants able to make starch.