Question

Explain how nitrification is different from nitrogen fixation. Mention the role of thiobacillus in nitrogen cycle? What do you understand by biological nitrogen fixation?

Answer 1

$nitrification$
✴️ nitrification is the process of converting ammonia first into nitrite and then into nitrate.

✴️ The process are carried out by soil bacteria that are chemoautotrophs.

✴️ Ammonia is oxidised into nitrite by Nitrosomonas and Nitrococcus.

✴️ Nitrite is oxidised to nitrate by Nitrobacter.

✴️ The nitrates are absorbed by plants and reduced to nitrites.

✴️ The nitrites are transport to leaves and reduced to ammonia, which forms the amino group of amino acids.

$nitrogen \: fixation$
✴️ The process of conversion of Nitrogen into ammonia and other Nitrogen compounds, is known as Nitrogen fixation.

✴️ In nature, lightning and ultraviolet radiation provide energy to convert Nitrogen into nitrogen oxides like N2o, NO and NO2.

✴️ Atmosphere also gets some amount of Nitrogen oxides from forest fire, automobiles exhaust industrial combustion and power nd generating station.

$role \: of \: tribacillus \:$
Thiobacillus carry out denitrification process wherein the nitrate present in the soil is reduced to nitrogen thus contributing to the atmospheric nitrogen.
$biological \: nitrogen \: fixation$
-The process by which living organisms convert the free atmospheric Nitrogen into ammonia is called biological nitrogen fixation.

-The nitrogen fixing micro organisms may be free living or symbionts.

-free living nitrogen fixers includes : Azotobacter and beijernickia(aerobes) Rhodospirillum and Clostridium(anaerobes) and Cyanobacteria like Nostoc and Aulosira.

-Symbionts nitrogen fixers includes :Rhizobium in the roots of legumes and Frankia in non legume like Alnus and Casuarina.

-symbiotic nitrogen fixation takes place in the root nodules of legume.

-During this process, a dinitrogen molecule is reduced by the addition of hydrogen atoms into two molecules of ammonia, catalysed by the enzyme nitrogenes.

_______hope it helps ✌️