Question

Photosynthesis in C${}_4$ plants is relatively less limited by atmospheric C$O_2$ levels because

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

Answer 1

The correct option is D the primary fixation of CO2 is mediated via PEP carboxylase.

Plants such as sugarcane and sorghum fix atmospheric carbon dioxide into phosphoenol pyruvic acid to produce oxaloacetic acid( a C${}_4$ acid) in the presence of phosphoenol pyruvate carbooxylase(PEP carboxylase). Such plants are called C${}_4$ plants.

In C${}_4$ plants, the primary product of OAA is mediated by PEP carboxylase, so it is relatively less limited by atmospheric CO${}_2$ levels.

So, the correct answer is 'The primary fixation of CO${}_2$ is mediated via PEP carboxylase'.