Page 20 - E-Biology Sec.2 2024-2025 U1_Handy
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C) Mechanism of photosynthesis
“The source of evolved oxygen”
The American Van Neil
Sulphur bacteria are autotrophic as they have bacteriochlorophyll.
They live in swamps and ponds where H2S is abundant as
the source of H2 to reduce CO2 to get carbohydrates & sulphur.
Van Neil assumptions
Green & purple sulphur bacteria Green plants
1. Light decomposes hydrogen sulphide (H2S) 1. Light decomposes water (H2O)
12H2S 12H2 + 12S 12H2O Chlorophyll 12H2 + 6O2
Bacteriochlorophyll
2. Resulted hydrogen reduces carbon dioxide into carbohydrates in dark reactions
Reduction
12H2 + 6CO2 C6H12O6 + 6H2O
Bacteriochlorophyll Chlorophyll
3. General equation for photosynthesis: 3. General equation for photosynthesis:
Bacteriochlorophyll Chlorophyll
Hydrogen sulphide is the source of oxygen. Water is the source of oxygen.
Dark reaction
Light reaction
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First Term
