What is the primary product of the Calvin cycle used for sugar synthesis?

What is the primary product of the Calvin cycle used for sugar synthesis?

• A. G3P.
• B. NADPH
• C. CO2
• D. H2O

Answer: (A)

Glyceraldehyde-3-phosphate is the main product exported from the Calvin cycle for sugar synthesis. During the cycle, carbon dioxide is fixed and, with ATP and NADPH from the light reactions, reduced to a three-carbon sugar phosphate called G3P. This molecule is the immediate building block for carbohydrates; two molecules of G3P can be converted into a six-carbon sugar like glucose. While most of the G3P is used to regenerate the carbon acceptor (RuBP) to keep the cycle going, the portion that leaves the cycle provides the starting point for sugar formation. NADPH serves as the reducing power inside the cycle but isn’t itself a sugar, CO2 is the substrate that becomes part of the carbohydrate, and water isn’t a product of the Calvin cycle. Hence, glyceraldehyde-3-phosphate is the primary product used for sugar synthesis.

Glyceraldehyde-3-phosphate is the main product exported from the Calvin cycle for sugar synthesis. During the cycle, carbon dioxide is fixed and, with ATP and NADPH from the light reactions, reduced to a three-carbon sugar phosphate called G3P. This molecule is the immediate building block for carbohydrates; two molecules of G3P can be converted into a six-carbon sugar like glucose. While most of the G3P is used to regenerate the carbon acceptor (RuBP) to keep the cycle going, the portion that leaves the cycle provides the starting point for sugar formation. NADPH serves as the reducing power inside the cycle but isn’t itself a sugar, CO2 is the substrate that becomes part of the carbohydrate, and water isn’t a product of the Calvin cycle. Hence, glyceraldehyde-3-phosphate is the primary product used for sugar synthesis.