Which of the following statements about the nitrogen cycle is false?

a. Ammonification converts organic nitrogenous matter from living organisms into ammonium (NH4 + ).

b. Denitrification by bacteria converts nitrates (NO3 − ) to nitrogen gas (N2 ).

c. Nitrification by bacteria converts nitrates (NO3 − ) to nitrites (NO2 − ).

d. Nitrogen fixing bacteria convert nitrogen gas (N2 ) into organic compounds.

Nitrogen Cycle is a biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere. It involves several processes such as nitrogen fixation, nitrification, denitrification, decay and putrefaction.

(c) Nitrification by bacteria converts nitrates (NO3 − ) to nitrites (NO2 − ).

• This statement is not correct because the nitrification is the process of conversion of ammonia intro nitrites and then to nitrates by bacteria. Hence this option is the correct option.

a. Ammonification converts organic nitrogenous matter from living organisms into ammonium (NH4 + ).

• This statement is correct because ammonia is made either from the excreta of the living organism or the decomposition of the dead plants and animals. Hence this option is incorrect.

b. Denitrification by bacteria converts nitrates (NO3 − ) to nitrogen gas (N2 ).

• This statement is correct because certain bacteria such as thiobacillusdenitrificans can converts nitrates to free nitrogen. Hence this option is not correct.

d. Nitrogen fixing bacteria convert nitrogen gas (N2 ) into organic compounds.

• This statement is true because nitrogen fixation is the process by which atmospheric nitrogen is converted into nitrates, nitrites or ammonia that can easily be assimilated by plants. Hence this option is not correct.