Answer: PEP carboxylase does not fix O2, reducing photorespiration in hot climates.
- A They fix the majority of their CO2 during the night using stored malate
- B PEP carboxylase does not fix O2, reducing photorespiration in hot climates
- C They universally require less water regardless of ambient temperature or humidity
- D They show a consistent growth advantage specifically in cold climates
Correct answer: B. PEP carboxylase does not fix O2, reducing photorespiration in hot climates
Explanation: C4 plants use PEP carboxylase (high affinity for CO2, no affinity for O2) in mesophyll, concentrating CO2 for Rubisco in bundle sheath: minimizing photorespiration.
Simplified photosynthesis diagram: light energy, CO2, and H2O enter the leaf and are converted in the chloroplast into glucose and O2.
Concept context
Light reactions, the Calvin cycle, C 3 /C 4 /CAM pathways, photorespiration, and factors affecting the rate of photosynthesis. One of the highest-yield NEET chapters.