Answer: PEP carboxylase does not fix O 2 , reducing photorespiration in hot climates.
- A They fix the majority of their CO<sub>2</sub> during the night using stored malate
- B PEP carboxylase does not fix O<sub>2</sub>, 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 O<sub>2</sub>, reducing photorespiration in hot climates
Explanation: C<sub>4</sub> plants use PEP carboxylase (high affinity for CO<sub>2</sub>, no affinity for O<sub>2</sub>) in mesophyll, concentrating CO<sub>2</sub> 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.