Question

The given figure of calvin cycle shows the carbon assimilation in $C_3$ plants. Choose the correct labelling of the carbohydrate molecule (Marked as I, II and III) involved in the Calvin cycle

• A. (I) - RuBP, (II) - Triose phosphate, (III) - PGA
• B. (I) - PGA , (II) - RuBP, (III) - Triose phosphate
• C. (I) - PGA , (II) - Triose phosphate, (III) - RuBP
• D. (I) - RuBP , (II) - PGA phosphate, (III) - Triose phosphate

Answer 1

Answer: (D)

Calvin cycle (also known as the Calvin-Benson cycle) is the set of chemical reactions that take place in stroma of the chloroplasts during photosynthesis. The cycle is lightindependent because it takes place after the energy has been captured from sunlight. The Calvin cycle proceeds in three stages:
1. Carboxylation $- CO _2$ is covalently linked to a carbon skeleton (RuBP)
2. Reduction - carbohydrate is formed at the expense of ATP and NADPH
3. Regeneration - the $CO _2$ acceptor RuBP reforms at the expense of ATP.
In the given figure of Calvin cycle, the labelling of carbohydrate molecule as I, II and III are respectively RuBP, PGA phosphate and triose phosphate.