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Difficulty: EasyPlant Nutrition and Photosynthesis

Arrange the following sequential stages of carbon assimilation in the Calvin cycle of photosynthesis in the correct order from start to finish.

  1. 1Fixation of carbon dioxide by ribulose 1,5-bisphosphate (RuBP)
  2. 2Reduction of 3-phosphoglycerate to triose phosphate using NADPH and ATP
  3. 3Regeneration of the carbon dioxide acceptor molecule, RuBP

Answer

The correct sequence from first to last is: Fixation of carbon dioxide by RuBP, Reduction of 3-phosphoglycerate to triose phosphate, and Regeneration of RuBP.
Carbon assimilation during the light-independent stage occurs in three distinct steps: initial carbon fixation where carbon dioxide is accepted by RuBP, reduction of 3-phosphoglycerate to sugar intermediates (triose phosphate) utilizing ATP and NADPH, and regeneration of RuBP to allow continuous carbon dioxide capture.

Step-by-Step Solution

1
Identify the primary carbon uptake event.
Atmospheric carbon dioxide is combined with RuBP to form 3-phosphoglycerate.
Enzymatic carbon fixation must occur first to introduce inorganic carbon into the biological system.
2
Trace energy input and chemical reduction.
3-phosphoglycerate is converted to triose phosphate.
ATP and reduced NADP (NADPH) generated from light-dependent reactions drive chemical reduction.
3
Identify the reset mechanism for the cycle.
Triose phosphate molecules are rearranged into RuBP.
Regenerating the primary acceptor RuBP allows the Calvin cycle to continue assimilating carbon dioxide.

Key Concept

Stages of Light-Independent Stage (Calvin Cycle)
Estimated Time:45s
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Topics

Plant Nutrition and Photosynthesis

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