Question

Anoxygenic photosynthesis is characteristic of
A. Rhodospirillum
B. Spirogyra
C. Chlamydomonas
D. Ulva

Answer 1

Hint: Anoxygenic photosynthesis is a type of photosynthesis that occurs more commonly in bacteria. It occurs under anaerobic conditions. It constitutes a photosynthetic electron chain in a non-cyclic manner. It also uses reduced electron donors such as hydrogen and ferrous ions.

Complete answer:
The anoxygenic photosynthesis usually occurs in anaerobic organisms that are found in hot springs, or most commonly in stagnant water. These organisms do not use water as their chemical agents so they do not produce oxygen as a by-product. They use hydrogen sulphide as their chemical agent and produce sulphur as a by-product. These are also known as sulphur bacteria.
Now let us understand some more about given options:
> Rhodospirillum :- it is a bacteria which is also known as sulphur bacteria. It is non – oxygenic bacteria. This bacteria possess anoxygenic photosynthesis. Thus this option is correct.
> Spirogyra :- it is a type of filamentous algae. Algae are oxygenic organisms. They do not perform anoxygenic photosynthesis.
> Chlamydomonas :- it is unicellular algae. Algae are oxygenic organisms. They do not perform anoxygenic photosynthesis.
> Ulva :- it is a sea lettuce, a common algae. Algae are oxygenic organisms. They do not perform anoxygenic photosynthesis.

Our required answer is A) Rhodospirillum.

Note: Oxygenic bacteria is also present in our environment. They produce oxygen as by product. They use water as a chemical reagent and produce oxygen. The well known example of oxygenic bacteria known till date are cyanobacteria and Cyanophyta.