Question

The process which makes major difference between $C_3$ and $C_4$ plants is

• A. Respiration
• B. Glycolysis
• C. Calvin cycle
• D. Photorespiration

Answer 1

The correct option is D Photorespiration

Photorespiration: It is inhibition of photosynthesis by high O${}_2$ level. It was termed as Warburg effect. However, the inhibition was observed mostly in C${}_3$ plants. The C${}_4$ plants were hardly affected by varying O${}_2$ concentrations. This is because of the spatial difference between the carbon dioxide fixation and the commencement of the C${}_3$ cycle in the C${}_4$ plants. The former occurs in the mesophyll cells, the latter occurs in the bundle-sheath cells.

Hence, the correct answer is 'Photorespiration'.