Question

Which one of the following organisms may respire in the absence of oxygen?

• A. Azotobacter
• B. Clostridium
• C. Rhizobium
• D. None of these

Answer 1

The correct option is B Clostridium

Clostridium is an anaerobic bacteria which respires in the absence of oxygen. It is a Gram-positive, rod-shaped bacteria. They are obligate anaerobes capable of producing endospores. It has the ability to produce a neurotoxin known as botulinum.

Azotobacter and Rhizobium are aerobic bacteria which helps in fixation of atmospheric nitrogen into the salts of nitrogen which is used by the plants for their metabolic activities.

So, the correct answer is option B.