Which one of the following categories of organisms do not evolve oxygen during photosynthesis?
Which one of the following categories of organisms do not evolve oxygen during photosynthesis?
Red algae
Photosynthetic bacteria
$\mathrm{C}_4$ plants with Kranz anatomy
Blue green algae
Solution
The photosynthetic bacteria (e.g. purple non-sulphur bacteria) photosynthesise using bacteriochlorophylls $a$ and $b$ in anoxic environments, such as the bottom mud of ponds and other stagnant water, although they are able to survive in air. The reducing agent involved is hydrogen rather than water, so oxygen is not produced. These bacteria efficiently use infrared light for photosynthesis.