Question

Where does C3 cycle take place ? Describe main events of CO2 fixation. What are the first and last stable products of CO2 fixation during photosynthesis ?

Answer 1

Dear Student,

The reactions of the C3 or Calvin cycle take place in the stroma that is the inner space of chloroplasts.

There are three stages of C3 cycle: carbon fixation, reduction and regeneration.
Carbon fixation:

• Ribulose 1, 5-bisphosphate combines with CO₂ to form a six-carbon compound that broken down into two molecules of a three-carbon compound, i.e., 3-phosphoglyceric acid (3-PGA). It is a stable organic intermediate.

• The reaction is catalysed by the enzyme RuBisCO (RuBP Carboxylase-Oxygenase).

The first stable product is 3-PGA and the last stable product is glucose.
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