Question

What is carbon fixation, and how does it relate to photosynthesis?

Answer 1

Hint: Carbon fixation is related to the Calvin cycle and photosynthesis is about obtaining chemical energy from solar energy.

Complete answer:
1)Carbon fixation is a part of the Calvin cycle where the inorganic carbon is converted to organic compounds. This Calvin cycle is also known as the light-independent phase or light-independent reactions because the reactions that occur in the Calvin cycle do not require any sunlight but it is dependent on the products that are obtained from the light-dependent phase which requires sunlight. Both this light-dependent and light-independent phase are part of photosynthesis.

2)The Calvin cycle is of three steps, where the first step is known as Carbon fixation where the carbon reacts with ribulose biphosphate (RuBP) which is a compound having 5 carbons to give 2 molecules of 3-phosphoglycerate that are 3-carbon compounds as a product. The carbon fixation is catalyzed by Ribulose bisphosphate carboxylase and ATP is also required for this reaction which is obtained from the light reactions of photosynthesis.

Note: Calvin cycle was discovered by Melvin Calvin and the Calvin cycle occurs in the stroma region of the chloroplasts. The other two steps of the Calvin cycle that occurs after the carbon fixation are reduction where 3-phosphoglycerate is reduced to form triose phosphate and Regeneration where the triose phosphate molecules are used to regenerate RuBP which can again start the Calvin cycle.