[Campbell Biology P.253] In the C4 photosynthetic pathway, which enzyme is responsible for t... | Practice Question

In the C4 photosynthetic pathway, which enzyme is responsible for the initial fixation of CO2 in mesophyll cells?

  • A: Rubisco
  • B: ATP synthase
  • C: PEP carboxylase
  • D: Malate dehydrogenase

Explanation

The C4 pathway initiates with PEP carboxylase adding CO2 to PEP in the mesophyll cells, forming oxaloacetate. This enzyme has a high affinity for CO2 and can function efficiently even at low CO2 concentrations, which is crucial for C4 plants.