Photosynthetic O2 production was measured in algae illuminated by single-wavelength light at 400, 500, 600, and 670 nm at equal photon flux.
The action spectrum suggests that:
- A
Wavelength has no effect.
- Bcheck_circle
Blue (400 nm) and red (670 nm) wavelengths drive photosynthesis most efficiently, matching chlorophyll absorption.
- C
Green light is most effective.
- D
Photosynthesis is more efficient at 500 nm than 670 nm.
Explanation
The action spectrum closely follows chlorophyll's absorption: blue and red are absorbed and drive photosynthesis; green is poorly absorbed and supports little O2 evolution.