Question

Select the wrongly matched pair with regard to $C_4$ - cycle.

• A. Primary $C{O}_2$ fixation-PGA product
• 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

The correct option is A Primary $C{O}_2$ fixation-PGA product

C4 pathway is observed in C4 plants like Maize. The primary $C{O}_2$ fixation product in $C_4$ cycle is oxaloacetic Acid (OAA) which is formed by the fixation of $C{O}_2$ in phosphoenol pyruvate in the mesophyll cells.
OAA then forms other 4C compounds like malic acid or aspartic acid in the mesophyll cells and transported to the bundle sheath cells.
In the bundle sheath cells, $C{O}_2$ in the 4C compounds is made use by the enzyme RUBISCO to generate chemical energy in the form of sugars.
PGA is the primary $C{O}_2$ fixation product of C3 cycle.