Question

Photosynthesis in $C_4$ plants is relatively less limited by atmospheric $C{O}_2$ levels, because

• A. Four carbon acids are the primary initial $C{O}_2$ fixation products
• B. The primary fixation of $C{O}_2$ is mediated via PEP carboxylase
• C. Effective pumping of $C{O}_2$ into bundle sheath cells
• D. Rubisco in $C_4$ plants has higher affinity for $C{O}_2$

Answer 1

Answer: (B)

The primary fixation of $C{O}_2$ is mediated via PEP carboxylase

Photosynthesis in $C_4$ plants is relatively less limited by atmospheric $C{O}_2$ levels, because the primary fixation of $C{O}_2$ is mediated via PEP carboxylase. At relatively low concentrations of $C{O}_2$, most $C{O}_2$ will be fixed by PEP carboxylase. $C_4$ pathway uses more energy than $C_3$ pathway.

So, the correct answer is option B.