Question: how did we discover plants use photosinthesis

Heidi Gardner answered on 13 Nov 2018:

Although photosynthesis has been around for millions of years, it wasn’t formally discovered by humans until the 1800s. Lots of different scientists contributed to the research that confirmed the existence of photosynthesis, and the work took more than 200 years to complete!

There were different stages to the discovery..

WATER – Jan Baptista van Helmont, a Belgian chemist, physiologist and physician, performed a 5-year experiment involving a willow tree which he planted in a pot with soil and placed in a controlled environment. The willow tree was carefully and precisely watered over the 5-year period. At the end of his experiment Helmont concluded that the growth of the tree was the result of the nutrients it had received from the water and not the soil. Helmont’s conclusion was inaccurate but his experiment proved that water contributes to the growth of plants.
Then work to confirm the need for AIR, OXYGEN and LIGHT, and CARBON DIOXIDE find out about each of those experiments here: https://photosynthesiseducation.com/discovery-of-photosynthesis/

The actual equation for photosynthesis wasn’t proposed until the 1930s, when Cornelis Van Niel came up with this:

CO2 + 2H2A + Light energy → [CH2O] + 2A + H2O

This eventually led to the simplified general equation that is commonly used today:

6CO2 + 6H2O + solar energy —-> C6H12O6 + O2