Question

The entire reaction of C${}_4$ pathway takes place in the

• A. Mesophyll and bundle sheath cells.
• B. Vascular bundle and palisade tissue.
• C. Mitochondria and peroxisome.
• D. Bundle sheath cells and endoplasmic reticulum.

Answer 1

The correct option is A Mesophyll and bundle sheath cells.

The first carbon fixation in C${}_4$ pathway occurs in mesophyll cells. The thin walled mesophyll cells of C${}_4$ have grana in the chloroplast and carry on initial carbon dioxide fixation with the help of PEP carboxylase enzyme. The PEP carboxylase enzyme carboxylates phosphoenol pyruvic acid or PEP and converts it into four carbon atom containing organic acids like oxaloacetic acid and malic acid. These organic acids are transported to bundle sheath cells, where they are subsequently decarboxylated to release carbon dioxide.

Thus, the correct answer is option A.