Question

Select the incorrectly matched pair with regard to the ${{C}_{4}}$ cycle.
A.Primary $C{{O}_{2}}$​ fixation product - PGA
B.Site of initial carboxylation - Mesophyll cells.
C.Primary $C{{O}_{2}}$ acceptor - PEP.
D.${{C}_{4}}$​ plant - Maize.
E.Location of enzyme $RuBisCO$- Bundle sheath cells

Answer 1

We know that we know that in most of the plants, Oxaloacetic acid which is a $3-$carbon containing compound is the $C{{O}_{2}}$ fixation product. But some plants also make use of Phospho-enol pyruvate (PEP) as the first product of $C{{O}_{2}}$.

Complete answer:
The plants which make use of phospho-enol pyruvate $\left( PEP \right)$ as the first product of $C{{O}_{2}}$ fixation is called as plants as $PEP$ is a $4-$carbon containing compound. The pathway is also called the Hatch-Slack pathway. First phospho-enol pyruvate (PEP) which is present in the mesophyll cells accepts $C{{O}_{2}}$ under the influence of the enzyme $PEP$ carboxylase. (Mesophyll cells of ${{C}_{4}}$ plants lack $RuBisCO$ and hence the normal pathway with $OAA$ is not used).
The primary $C{{O}_{2}}$ fixation product in${{C}_{4}}$ plants is oxaloacetic acid, which is converted to malic acid or aspartic acid that is transported to the bundle sheath cells where the acid is decarboxylated and the $C{{O}_{2}}$ thus released enters the Calvin cycle.
Oxaloacetic acid is the primary $C{{O}_{2}}$ fixation product of ${{C}_{4}}$ cycle. It occurs in several plants like sugarcane, maize, sorghum etc.
Therefore, the correct answer is option A.

Note:
Remember that Phospho-enol pyruvate (PEP) is the first carbon dioxide product in pathway and Oxaloacetic acid (OAA) is the first carbon dioxide fixation product in plants that show ${{C}_{3}}$ pathway or what is also known as Calvin cycle.