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NEET2026BiologyChapterActual

During the Calvin cycle, the primary carbon dioxide acceptor is a:

Options

  1. A3-carbon organic acid
  2. B5-carbon ketose sugar
  3. C4-carbon dicarboxylic acid
  4. D6-carbon aldohexose

Correct answer

B. 5-carbon ketose sugar

Step-by-step solution

The primary carbon dioxide acceptor in the Calvin cycle is Ribulose-1,5-bisphosphate (RuBP). RuBP is a 5-carbon ketose sugar. It combines with CO₂ in the presence of the enzyme RuBisCO to form two molecules of 3-phosphoglyceric acid (3-PGA), which is the first stable product of the cycle. Answer: 5-carbon ketose sugar

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