explain how does atmospheric nitrogen, which is an integral part of the living bodies, get introduced in living organisms
Answers
Nitrogen is the most abundant element in our planet’s atmosphere. Approximately 78% of the atmosphere is made up of nitrogen gas (N2).
Plant uptake of nitrogen compounds
Once nitrogen is converted into compounds like ammonium and nitrate, these can be taken up from soils by plants and then the nitrogen can be used to form macromolecules like proteins and nucleic acids (DNA and RNA).
Nitrogen is a crucially important component for all life. It is an important part of many cells and processes such as amino acids, proteins and even our DNA. It is also needed to make chlorophyll in plants, which is used in photosynthesis to make their food.
As part of these life processes, nitrogen is transformed from one chemical form to another. The transformations that nitrogen undergoes as it moves between the atmosphere, the land and living things make up the nitrogen cycle.
Fixation
Nitrogen in its gaseous form (N2) can’t be used by most living things. It has to be converted or ‘fixed’ to a more usable form through a process called fixation. There are three ways nitrogen can be fixed to be useful for living things:
Biologically: Nitrogen gas (N2) diffuses into the soil from the atmosphere, and species of bacteria convert this nitrogen to ammonium ions (NH4+), which can be used by plants. Legumes (such as clover and lupins) are often grown by farmers because they have nodules on their roots that contain nitrogen-fixing bacteria. (Learn more about this process in the article The role of clover.)
Through lightning: Lightning converts atmospheric nitrogen into ammonia and nitrate (NO3) that enter soil with rainfall.
Industrially: People have learned how to convert nitrogen gas to ammonia (NH3-) and nitrogen-rich fertilisers to supplement the amount of nitrogen fixed naturally.