Describe the main chemical changes which occur during photosynthesis in
(i) Light reaction (ii) Dark reaction.
Describe the main chemical changes which occur during photosynthesis in
(i) Light reaction (ii) Dark reaction.
Photosynthesis is a complex process of synthesis of organic food materials. It is both a oxidation and a reduction process. Here water is oxidised and carbon dioxide is reduced to carbohydrates.
Now Photosynthesis takes place in two steps:
i) light reaction - Or light dependent reaction
ii) dark reaction- Light independent reaction.
Light Reaction is the first stage in photosynthesis where water is broken in the chlorophyll molecule into H+ ions and OH- ions in the presence of light through a process called photlolysis. This results in the in the formation of assimilatory powers such as NADPH2 and ATP . It occurs in the grana of chloroplast.
Dark Reaction is the second step in the process of photosynthesis. The chemical processes of photosynthesis occurring in the phase independent of light is called dark reaction. It takes place in the stroma of the chloroplast. The Dark reaction of photosynthesis is purely enzymatic and it is slower than the light reaction. In dark reactions, two types of cyclic reaction occur.
They are
- Calvin cycle or C3 Cycle
- Hatch Slack Cycle or C4 cycle.
In dark reaction, sugars are synthesised from CO2. The energy poor carbon dioxide is fixed to energy rich carbohydrates using the energy rich compound ATP and the assimilatory power NADPH2 of light reaction. This process is called carbon fixation.
Blackman had first demonstrated the existence of dark reaction .Hence it is known as Blackman’s reaction.
Photosynthesis is a complex process of synthesis of organic food materials. It is both a oxidation and a reduction process. Here water is oxidised and carbon dioxide is reduced to carbohydrates.
Now Photosynthesis takes place in two steps:
i) light reaction - Or light dependent reaction
ii) dark reaction- Light independent reaction.
Light Reaction is the first stage in photosynthesis where water is broken in the chlorophyll molecule into H+ ions and OH- ions in the presence of light through a process called photlolysis. This results in the in the formation of assimilatory powers such as NADPH2 and ATP . It occurs in the grana of chloroplast.
Dark Reaction is the second step in the process of photosynthesis. The chemical processes of photosynthesis occurring in the phase independent of light is called dark reaction. It takes place in the stroma of the chloroplast. The Dark reaction of photosynthesis is purely enzymatic and it is slower than the light reaction. In dark reactions, two types of cyclic reaction occur.
They are
- Calvin cycle or C3 Cycle
- Hatch Slack Cycle or C4 cycle.
In dark reaction, sugars are synthesised from CO2. The energy poor carbon dioxide is fixed to energy rich carbohydrates using the energy rich compound ATP and the assimilatory power NADPH2 of light reaction. This process is called carbon fixation.
Blackman had first demonstrated the existence of dark reaction .Hence it is known as Blackman’s reaction.
