Question

what is the main function of nitrogen fixing bacteria?
a. convert n2 into ammonia
b. convert ammonia into atmospheric nitrogen
c. return nirtogen in feces to the plants

Explanation:

Nitrogen - fixing bacteria play a crucial role in the nitrogen cycle. They have the ability to take atmospheric nitrogen (\(N_2\)) which is relatively inert and convert it into ammonia (\(NH_3\)). This ammonia can then be further processed (e.g., through nitrification) into forms that plants can use for growth. Option b is incorrect because it is the opposite of what nitrogen - fixing bacteria do (denitrifying bacteria convert nitrates to atmospheric nitrogen in some cases). Option c is not the main function of nitrogen - fixing bacteria; decomposers are more involved in returning nitrogen from feces and dead organisms to the soil in general forms, and then nitrogen - fixing (and other nitrogen - cycle related bacteria) act on it.

Answer:

A. Convert N2 into Ammonia