What is the first stable chemical product formed after carbon fixation in the C3 pathway?
Answer and explanation
Correct answer: A. 3-Phosphoglycerate
- Step 1: RuBisCO carboxylates RuBP to form an unstable 6-carbon intermediate. Step 2. This intermediate immediately hydrolyzes into two molecules of 3-phosphoglyceric acid (a 3-carbon compound), giving C3 photosynthesis its name. Answer: 3-Phosphoglyceric acid (3-PGA). Why not the others: OAA is the first stable product in C4 plants (4 carbons); malic acid is a downstream C4 intermediate; glucose is formed after reduction and regeneration stages.
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