Question

Photosynthesis in C4 plants is relatively less limited by atmospheric CO2 levels because :

• A. four carbon acids are the primary initial CO2 fixation products
• B. the primary fixation of CO2 is mediated via PEP carboxylase
• C. effective pumping of CO2 into bundle sheath cells
• D. RUBISCO in C4 plants has higher affinity for CO2

Answer 1

Answer: (B)

the primary fixation of CO2 is mediated via PEP carboxylase

Answer 2

Plants like sugarcane and sorghum employ a unique mechanism wherein they convert atmospheric carbon dioxide into oxaloacetic acid, a C4 compound, through the action of phosphoenol pyruvate carboxylase (PEP carboxylase). These plants are categorized as C4 plants. In C4 plants, the primary formation of oxaloacetic acid (OAA) is facilitated by PEP carboxylase, making them less susceptible to limitations imposed by atmospheric CO2 levels.

So, the correct option is (B): The primary fixation of CO2 is mediated via PEP carboxylase