Question Detail
Question
In the Calvin-cycle, the joining of phosphoenol pyruvate to carbon dioxide leads to formation of.
Correct Answer
Option B is the correct answer.
Detailed Explanation
This question appears to confuse the C3 and C4 pathways. In C4 plants, the initial carbon fixation involves the enzyme PEP carboxylase combining CO2 with phosphoenolpyruvate (PEP) to form the 4-carbon compound oxaloacetate. This occurs in mesophyll cells. In the Calvin cycle (which takes place in bundle sheath cells of C4 plants, or in all mesophyll cells of C3 plants), the first step is RuBP + CO2 -> 3-PGA. Based on the phrasing, it's describing the C4 pathway, so the product is oxaloacetate.
Hint
In plants like maize and sugarcane, what is the first product when CO2 is fixed by PEP?