01 DEFINITION Recall the history of photosynthesis Many scientists have contributed to understanding how plants carry out photosynthesis. These are as follows: Van Helmont (1648) concluded that all food of the plant is derived from water and not from the soil. Stephen Hales (Father of Plant Physiology) (1727) reported that plants obtain a part of their nutrition from air and light may also play a role in this process. Joseph Priestley (1772) demonstrated that green plants purify the foul air (i.e., Phlogiston), produced by burning of the candle, and convert it into the pure air (i.e., Dephlogiston). Jan Ingen-Housz (1779) concluded by his experiment that purification of air was done by green parts of the plant only and that too in the presence of sunlight. Green leaves and stalks liberate dephlogisticated air during sunlight and phlogisticated air during dark. Jean Senebier (1782) proved that plants absorb CO and release O in presence of light. He al...
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