Describe the nitrogen cycle

K.C.S.E Biology Q & A - MODEL 2008PP2QN07

Describe the nitrogen cycle

answers

​During thunderstorm/ lightning; nitrogen gas  combines with O2 to form nitrogen  oxides; nitrogen  oxides dissolve in water to for nitric acid; acid is deposited in the soil by rain, nitric acid combines with chemical substance to  form  nitrates/ nitric acids dissolves to form nitrates which are  absorbed  by plants symbiotic bacteria/ such as rhizobium; which are  found in root nodules of leguminous  plants, fix free nitrogen to  nitrates.
Free living bacteria/ clatridium/ azotobacteria fix nitrogen to all rates
Nostoc algae/ chlorella/ anaemia/ ix nitrogen to nitrates.
Plants use Nitrates to form plant proteins
Animals feed on plants and convert  plant proteins into animal proteins
Plants/ animals die and decomposed by bacteria/ saprophytes/ fungi decomposing  plants/ animals/ release ammonia which is covered to nitrates/ by nitrosomomes nitrococcus bacteria 
Nitrates  are converted to nitrates; by  nitrobacteria
Nitrates in the soil can be converted to free nitrogen/ denitrification by some  fungi; pseudomonas/ hulobacillus denitrifying bacteria.