Question

define nitrification and denitrification

Answer 1

Nitrification is the biological oxidation of ammonia  to nitrite followed by the oxidation of the nitrite to nitrate. The transformation of ammonia to nitrite is usually the rate limiting step of nitrification. Nitrification is an important step in the nitrogen cycle in soil. Nitrification is an aerobic process performed by small groups of autotrophic bacteria .

Denitrification is a process where nitrate is reduced and ultimately produces molecular nitrogen  through a series of intermediate gaseous nitrogen oxide products. 

Answer 2

nitrogen cycle nitrification is the biological oxidation of ammonia or ammonium to nitrite followed by the oxidation of the nitrite to nitrate nitrification is an important step in the nitrogen cycle in soil nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea