[Campbell Biology P.252] Which of the following statements accurately describes the enzyme P... | Practice Question

Which of the following statements accurately describes the enzyme PEP carboxylase as discussed in the context of C4 plants?

  • A: It is found exclusively in mesophyll cells and has a much higher affinity for CO2 than rubisco, with no affinity for O2.
  • B: It is found in bundle-sheath cells and initiates the Calvin cycle by binding CO2 and O2.
  • C: It is the primary enzyme for carbon fixation in C3 plants when stomata are closed.
  • D: It generates ATP during photorespiration, making the process energetically favorable.

Explanation

The text explicitly states that PEP carboxylase is an enzyme present only in mesophyll cells that has a much higher affinity for CO2 than rubisco and no affinity for O2. This unique property is key to C4 plants' efficiency in hot, arid climates.