VerifiedHint: Conversion of ammonia into nitrite and nitrate is done by nitrifying bacteria which are Nitrosomonas, Nitrosococcus, Nitrobacter, etc. It is an important step in the Nitrogen cycle in soil.
Complete answer:
> Option A is Ammonification. It is a process where there is conversion of atmospheric nitrogen into ammonia by the help of bacteria known as ammonifying bacteria, for example, Rhizobium, Azotobacter, etc. But in this question that process is asked in which there is conversion of ammonia into nitrite and nitrate and therefore, this option is incorrect and it gets eliminated.
> Option B is Denitrification. It is a process where there is conversion of nitrites and nitrates into free nitrogen by the help of denitrifying bacteria, for example, Thiobacillus denitrificans, Micrococcus, etc. But in this question that process is asked in which there is conversion of ammonia into nitrite and nitrate and therefore, this option is incorrect and it gets eliminated.
> Option C is Nitrification. It is a process in which there is conversion of ammonia into nitrite and nitrates with the help of nitrifying bacteria, for example, Nitrosomonas, Nitrosococcus, Nitrobacter, etc. In this question, this same conversion is asked and therefore, this option is the correct one.
- The process of converting the ammonia to nitrates involves, mainly two steps, which include the conversion of ammonia to nitrates, and these nitrites further converted to nitrates.
- During the first step of conversion of ammonia to nitrite, ammonia is oxidized by ammonia-oxidizing bacteria.
NH3 + O2 → NO2– + 3H+ + 2e–
- Next in order to convert nitrite to nitrate, they require nitrite-oxidizing bacteria.
NO2– + H2O → NO3– + 2H+ +2e–
- The enzymes required are ammonia monooxygenase and hydroxylamine oxidoreductase.
- Nitrification is very important because it shows the availability of nitrogen as fertilizer.
> Option D is All of the above. This option is incorrect since ammonification and denitrification are not the process of conversion of ammonia into nitrites and nitrates but nitrification is the process of conversion of ammonia into nitrites and nitrates.
Hence, the correct answer is option (C).
Note: Ammonification is conversion of nitrogen into ammonia and denitrification is conversion of nitrites and nitrates into free nitrogen. In both terrestrial and aquatic systems, nitrifying bacteria release the greenhouse gases and nitrous oxide, through the pathway known as nitrifying denitrifier, and an environment, they are deducted by pH, temperature, etc.
