Question

During dark reaction for fixation of carbon, three carbon atoms of each molecule of 3-PGA are derived from

Answer 1

The Calvin cycle is the biosynthetic phase of the photosynthesis during which ATP and NADPH are used for carbon fixation. Calvin cycle has three phases:

● Carboxylation
● Reduction
● Regeneration

In the carboxylation reaction, ribulose 1,5 bisphosphate (RuBP) a 5C compound combines with one carbon compound-carbon dioxide to form a 6C unstable intermediate.

This intermediate splits into two molecules of a 3 carbon compound phosphoglyceric acid (PGA). This reaction is catalysed by the enzyme RuBP carboxylase (RuBisCO)