PHOTOSYNTHESIS

PHOTOSYNTHESIS
          - a complex process that uses light energy to convert carbon dioxide and water into carbohydrates.


Discoveries on Photosynthesis


Jan van Helmont
          - Flemish botanist
          - first who studied photosynthesis
          - on 1630 he concluded that plants make their own organic materials and donot get these from the
             soil. 


Joseph Priestly
          - in 1772, he showed that a sprig of mint would restore air that had been injuredby a burning
            candle.
          - the results showed that oxygen gas, which is used up in burning, is released by plants.


Jan Ingenhouz         
          - supported the findings of Priestly
          - in 1779, he added that this air (oxygen) could only be restored by plants with sunlight.


Nicholas de Saussure
          - in1804, he made an experiment and its results showed that the increase in the dry weight of the plant
           was greater than the weight of the carbon dixide removed from the air.
          - concluded that aside from carbon dioxide, the other substance that contributed to the increase in the
           weight of the plant was water.


C. B. van Niel
          - in the 1930s, he was able to proved that light splits water, producing oxygen.


General Outline of Photosynthesis
carbon dioxide + water + light energy ----> organic material + oxygen + water


2 CLASSIFICATIONS


Heterotrophs
          - also called as "other-feeders"
          - cannot synthesize their own food and depend on autotrophs


Autotrophs
          - also called as "self-feeders"
          - synthesize their own food
          - has 2 main types:
               : photoautotrophs - include green plants and purple bacteria
               : chemoautotrophs - includes bacteria

 OXIDATION-REDUCTION PROCESS or REDOX REACTIONS
                     - involve the stable transfer of electrons between atoms.
It is said to be:

     Reduced - when an atom gains one or more electrons
     Oxidized - when it loses one or more electrons