Which of the following step does not occur in Calvin cycle?

The correct answer is Oxidation

Concept:

• The Calvin Cycle, also known as the C3 cycle, is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms.
• This cycle is responsible for the fixation of carbon dioxide and its conversion into glucose, which is a primary source of energy for the plant. For e.g., rice, wheat, oats, barley, cotton, peanuts, etc. are C3 plants.
• The Calvin Cycle consists of three main stages: Carboxylation, Reduction, and Regeneration.

Explanation:​

• Carboxylation: This is the first stage of the Calvin Cycle where CO2 is fixed from the atmosphere. It involves the enzyme RuBisCO catalyzing the reaction between CO2 and ribulose-1,5-bisphosphate (RuBP) to form 3-phosphoglycerate. This step does not utilize ATP.
• Reduction: This is the second stage of the Calvin Cycle. In this stage, ATP and NADPH produced during the light reactions are used to convert 3-phosphoglycerate into glyceraldehyde-3-phosphate (G3P). Specifically, ATP provides the energy for the phosphorylation of 3-phosphoglycerate to 1,3-bisphosphoglycerate.
• Regeneration: This is the third stage of the Calvin Cycle. During this stage, ATP is utilized to regenerate ribulose-1,5-bisphosphate (RuBP) from glyceraldehyde-3-phosphate (G3P). This regeneration is essential for the cycle to continue and to ensure that carbon fixation can proceed uninterrupted.