Answer: night.
- A night
- B noon
- C dawn only
- D never
Correct answer: A. night
Explanation: CAM plants (e.g. cacti) take in CO₂ at night, keeping stomata shut in the hot day.
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.