Answer: Rubisco fixes O2 instead of CO2, reducing efficiency.
- A Plants carry out ordinary mitochondrial respiration mainly during daylight hours
- B Rubisco fixes O2 instead of CO2, reducing efficiency
- C Captured light energy is redirected to drive mitochondrial ATP synthesis
- D CO2 is released mainly during the dark hours of the night
Correct answer: B. Rubisco fixes O2 instead of CO2, reducing efficiency
Explanation: Photorespiration: at high O2/low CO2, Rubisco adds O2 instead of CO2 to RuBP. This wasteful process reduces photosynthesis efficiency in C3 plants.
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.