Question

"Phosphoenylpyruvate carboxylase (PEPCase) fixes carbon dioxide(C1) to PEP(C3) to form oxaloacetate(C4) within mesophyll cells of the C-4 plants.

A True
B False"

Answer 1

PEP carboxylase fixes CO2 to PEP to form oxaloacetate in the mesophyll cells of C4 plants, indicating that the statement is (Option A) true.

Step-by-step explanation:

Phosphoenylpyruvate carboxylase (PEPCase) is indeed responsible for fixing carbon dioxide (CO₂) to phosphoenolpyruvate (PEP), a three-carbon compound, to form oxaloacetate (OAA), a four-carbon compound, in the mesophyll cells of C4 plants. This is the first step in the C4 photosynthetic pathway, where high concentrations of PEP carboxylase enable rapid carbon dioxide fixation to produce OAA, which is then converted to malic acid and transported to bundle sheath cells. In these adjacent cells, malic acid is decarboxylated, releasing CO₂ for fixation by the enzyme ribulose bisphosphate carboxylase (RuBisCO) in the Calvin cycle, which is the standard pathway for carbon fixation in photosynthesis.