C4 Plants and Photorespiration Prevention — NEET Biology
✅ Asked in NEET 2016In C₄ plants photorespiration does not occur. This is because they have a mechanism that increases the concentration of CO₂ at the enzyme site. This takes place when the C₄ acid from the mesophyll is broken down in the bundle sheath cells to release CO₂ – this results in increasing the intracellular concentration of CO₂. In turn, this ensures that the RuBisCO functions as a carboxylase minimising the oxygenase activity.
C4 plants avoid photorespiration by concentrating CO₂ inside bundle sheath cells, forcing RuBisCO to act as a carboxylase instead of an oxygenase. Students often confuse this with C3 plants and don't understand that the C4 acid breakdown in bundle sheaths is the key mechanism. The common mistake is thinking photorespiration is completely absent in all plants or that it's simply avoided by CO₂ availability in the atmosphere. Remember: C4 plants use a spatial separation strategy (mesophyll → bundle sheath) to maintain high intracellular CO₂, ensuring RuBisCO performs carboxylation, not oxygenation. This distinction between C3 and C4 pathways is fundamental to understanding plant adaptation to different environments.
This paragraph was tested 2 times in NEET.
The process which makes major difference between C₃ and C₄ plants is: (NEET 2016 Phase 2)
Q33. A plant in your garden avoids photorespiratory losses, has improved water use efficiency, shows high rates of photosynthesis at high temperatures and has improved efficiency of nitrogen utilisation. In which of the following physiological groups would you assign this plant? (NEET 2016 Phase 1)
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