Put potassium hydroxide pellets or potassium hydroxide solution in the bottle.

Potassium hydroxide absorbs carbon dioxide. Insert splitted cork in the mouth of the bottle.

Insert one of the leaf of destarched plant (through a split cork) into transparent bottle containing potassium hydroxide pellets/potassium hydroxide solution.

Leave the plant in sunlight. After a few hours, test this leaf and any other leaf of this plant for presence of starch, as mentioned in activity-1. The leaf par

t which was exposed to the atmospheric air and light becomes bluish-black, and the one inside the bottle containing potassium hydroxide which absorbs carbon dioxide in the bottle remains colourless. This proves that carbon dioxide is necessary for photosynthesis.

Why was the plant kept in dark and then in sun light ?

Why did we test two leaves in this experiment?

We have so far discussed the role of water and gases in the process of photosynthesis. Scientist who had been working on these lines had observed some other factors that affect the process of photosynthesis.

Light and Photosynthesis In Priestley’s time, scientists didn’t understand about energy, but later on much was discovered about it. If energy is released when carbon dioxide and water is formed by combining oxygen with carbon and hydrogen, then

what about the reverse?.

What about forming oxygen again and putting it back in the air. Eventually, scientists learned that the energy situation would also reverse.

Oxygen formation would use up energy. That means if plants