CBSE Class 10 Answered
Calvin cycle or dark reaction is a synthetic process in which carbon dioxide is reduced to carbohydrates. It takes place in the stroma of chloroplasts. The entire process runs in a cycle. It utilizes ATP and NADPH2. This reaction is independent of light.
The Calvin cycle begins when a molecule of carbon dioxide bonds with the five-carbon sugar ribulose diphosphate. A series of reactions ensue (which involve the NADPH molecule from noncyclic electron flow and convert it back to an NADP+ molecule), producing another molecule of ribulose diphosphate and a molecule of glyceraldehyde phosphate.
This cycle goes in cycles. For every one complete turn of the cycle fixes one CO2 molecule and regenerates an RuBP molecule. Calvin Benson cycle consists of three subsequencing stages: CO2 fixation, CO2 reduction, and regeneration of ribulose bisphosphate (RuBP). In this process, carbon dioxide is reduced to carbohydrates. This reaction utilises ATP and NADPH2.