Photosynthesis is the process that converts inorganic molecules into organic molecules such as glucose. The organic molecules formed can be used as a source of energy or for forming other more complex molecules. Because organisms that photosynthesise can create their own respiratory substrates they are said to be autotrophic. This essentially means they do not need a food source. Humans by contrast are heterotrophic, they need to ingest organic molecules from a biological source to use as their respiratory substrates.
Photosynthesis is essentially the reverse of respiration. The overall summary equation is usually written as:
|carbon dioxide + water (+ light energy) glucose + oxygen
|6CO2 + 6H2O (+light energy) C6H12O6 + 6O2
This equation is a simplification of a process that contains a series of reactions. The reactions in photosynthesis can be grouped into two stages, these are the:
- Light Dependent reactions
- Light Independent reactions
All the reactions of photosynthesis take place in the chloroplasts of green plants