Question

Which one of the following is a unicellular, non-motile desmid?

• A. Chromatium
• B. Cosmarium
• C. Chlorobium
• D. Clostridium

Answer 1

The correct option is B Cosmarium

A. Chromatium is a rod-shaped gram-negative purple sulphur bacteria found in water.

B. Cosmarium is a unicellular desmid which consists of two round semicells separated by a constriction. Its usually non-motile but motility can be induced by light.

C. Chlorobium is a gram-negative green sulphur bacteria and is found in hot springs where the environment is sulphide rich.

D. Clostridium is a gram-positive anaerobic bacteria which causes botulism and other infectious diseases like diarrhoea.

So, the correct answer is 'Cosmarium'.