What is the primary CO2 acceptor molecule in the C3 photosynthetic pathway (Calvin Cycle)?
Answer and explanation
Correct answer: B. Ribulose-1,5-bisphosphate
- Step 1: In the Calvin cycle, atmospheric CO2 enters the stroma of chloroplasts. Step 2. RuBP (a 5-carbon ketose sugar) acts as the initial carbon acceptor in a reaction catalyzed by the enzyme RuBisCO. Answer: Ribulose-1,5-bisphosphate (RuBP). Why not the others: PEP is the primary CO2 acceptor in C4 plants; OAA is the first stable product in C4 plants; 3-PGA is the first stable 3-carbon product of the C3 cycle.
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