Question

Match the following.

(A) Nitrobacter	(i) Free living aerobic nitrogen fixing organism
(B) Clostridium	(ii) Converts nitrite to nitrates
(C) Nitrosococcus	(iii) Converts ammonia to nitrite
(D) Azotobacter	(iv) Free living anaerobic nitrogen fixing organism

• A. A- (iii), B- (iv), C- (ii), D- (i)
• B. A- (i), B- (ii), C- (iii), D- (v)
• C. A- (ii), B- (iv), C- (iii), D- (i)
• D. A- (iv), B- (ii), C- (i), D- (iii)

Answer 1

The correct option is C A- (ii), B- (iv), C- (iii), D- (i)

Nitrobacter plays an important role in the nitrogen cycle. They oxidize nitrite to nitrate in the soil. Nitrobacter uses energy from the oxidation of nitrite ions (NO${}_2$-), into nitrate ions (NO${}_3$-), to fulfill their energy needs. Clostridium is obligate anaerobe that cannot tolerate oxygen even if they are not fixing nitrogen. They live in habitats low in oxygen, such as soils and decaying vegetable matter. The last step in the process of aerobic ammonia oxidation is carried out by groups of nitrifying bacteria such as Nitrosococcus which convert ammonia to nitrite. Azotobacter is aerobic, free-living soil microbe which binds atmospheric nitrogen, which is inaccessible to plants and releasing it in the form of ammonium ions into the soil.