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

Hint: 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.