Question

In $C_4$ plants, the carbon dioxide fixation occurs in

• A. Guard cells
• B. Spongy cells
• C. Palisade cells
• D. Bundle sheath cells

Answer 1

The correct option is D Bundle sheath cells

$C_4$ plants conduct $C_4$ cycle in mesophyll cells and Calvin cycle (fixation of carbon) in bundle sheeth cells. The C4 pathway in mesophyll cells includes carboxylation of phosphoenolpyruvate into oxaloacetate. The oxaloacetate is then converted into the intermediate malate, which is transported bundle-sheath cell. Malate is decarboxylated to produce pyruvate and enters the Calvin cycle. Correct answer is D.