Question

Match column I and II and select the correct option.

	List I		List II
A	Aerobic	1	Frankia
B	Non-photosynthetic bacteria	2	Azospirillum
C	Casuarina	3	Clostridium
D	Tropical grasses	4	Azotobacter

• A. A- 2, B- 3, C- 1, D- 4
  
• B. A- 1, B- 2, C- 3, D- 4
• C. A- 2, B- 3, C- 4, D- 1
• D. A- 4, B- 3, C- 2, D- 1

Answer 1

The correct option is A A- 2, B- 3, C- 1, D- 4

Nitrogen fixation is a process in which atmospheric nitrogen is converted into nitrites and nitrates to be absorbed by plants. Plants can not take nitrogen present in the atmosphere directly, certain bacteria help to fix atmospheric nitrogen to ammonium or nitrate. There are two types of nitrogen-fixing bacteria: symbiotic (Rhizobium and Frankia) and free-living (Azotobacter and Clostridium).
Frankia is filamentous, it is found in the root nodules of trees like Ulnus and Casurina.
Azospirillum is an aerobic, free living, nitrogen fixing bacteria. It is found in association with plant roots where it plays important role in plant growth and fixes atmospheric nitrogen.
Clostridium is a non-photosynthetic nitrogen-fixing genus.
Nitrogen fixation in Azotobacter takes place in the roots of tropical grasses.

Thus, the correct answer is option A.