Question

The nitrogen found in the atmosphere is not in a form that plants and animals can use. What converts the nitrogen into a usable form?

Answer 1

The process of converting atmospheric Nitrogen into a usable form is called Nitrogen fixation.

Explanation:

Atmospheric Nitrogen is `N_2` which has a very strong triple bond. This makes it almost inert. For Nitrogen to be usable the triple bond needs to be broken. A very common mechanism is to turn `N_2` into ammonia `NH_3`. This is called Nitrogen fixation.

Nitrogen can be fixed by lightning which breaks the chemical bonds to form Nitrogen oxides `NO` and `NO_2`.

Bacteria and some plants have an enzyme called nitrogenase which can convert atmospheric Nitrogen into ammonia.

Nitrogen is an essential element for making fertilisers and explosives. The Haber process was developed in 1909 which passes Nitrogen and Hydrogen at high temperatures and pressures over catalysts to make ammonia. Hundreds of million tonnes of ammonia are produced every year by this process.

Answer 2

• Nitrogen is 78% in air but is not available for use by plants and animals without being fixed .

Explanation:

• Nitrogen must be fixed or combined with other elements like oxygen by prokaryotes

• The common bacteria Rhizobium leguminosarum living in root nodules of legumes such as peas .

• The bacterias takes up free nitrogen from the atmosphere and converts into soluble nitrates such as potassium nitrate.

• These nitrates transfer into soil, absorbed by plants which makes their protein from it.