Explain briefly about Nitrogen Cycle
Answers
Answer:
The nitrogen cycle is the biogeochemical cycle by which nitrogen is converted into multiple chemical forms as it circulates among atmosphere, terrestrial, and marine ecosystems. Important processes in the nitrogen cycle include fixation, ammonification, nitrification, and denitrification.
Definition
The nitrogen cycle refers to the cycle of nitrogen atoms through the living and non-living systems of Earth. The nitrogen cycle is vital for life on Earth. Through the cycle, atmospheric nitrogen is converted to a form which plants can incorporate into new proteins.
Nitrogen Cycle Explained
Nitrogen was originally formed in the hearts of stars through the process of nuclear fusion. When ancient stars exploded, they flung nitrogen-containing gases across the Universe. When the Earth was formed, nitrogen gas was the main ingredient in its atmosphere.
Today, the Earth’s atmosphere is about 78% nitrogen, about 21% oxygen, and about 1% other gases. This is an ideal balance because too much oxygen can actually be toxic to cells. In addition, oxygen is flammable. Nitrogen, on the other hand, is inert and harmless in its gaseous form. However, nitrogen gas is not accessible to plants and animals for use in their cells.
Here we will discuss how nitrogen plays a vital role in the chemistry of life – and how it gets from the atmosphere, into living things, and back again.
Nitrogen Cycle Steps
The basic steps of the nitrogen cycle are illustrated here:
Look at the image that i have attached
We’ll discuss each part of the process below.
Nitrogen Fixation
In the process of nitrogen fixation, bacteria turn nitrogen gas from the atmosphere into ammonia.
These nitrogen-fixing bacteria, often called “diazotrophs,” have an enzyme called “nitrogenase” which combines nitrogen atoms with hydrogen atoms. Ammonia is a nitrogen compound that can dissolve in water, and is easier for other organisms’ enzymes to interact with.
Nitrification
In nitrification, a host of soil bacteria participate in turning ammonia into nitrate – the form of nitrogen that can be used by plants and animals. This requires two steps, performed by two different types of bacteria.
First, soil bacteria such as Nitrosomonas or Nitrococcus convert ammonia into nitrogen dioxide. Then another type of soil bacterium, called Nitrobacter, adds a third oxygen atom to create nitrate
Assimilation
In nitrogen assimilation, plants finally consume the nitrates made by soil bacteria and use them to make nucleotides, amino acids, and other vital chemicals for life.
Plants take up nitrates through their roots and use them to make amino acids and nucleic acids from scratch. Animals that eat the plants are then able to use these amino acids and nucleic acids in their own cells.
Ammonification
Now we have moved nitrogen from the atmosphere into the cells of plants and animals.
Because there is so much nitrogen in the atmosphere, it may seem that the process could stop there – but the atmosphere’s supply is not infinite, and keeping nitrogen inside plant and animal cells would eventually result in big changes to our soil, our atmosphere, and our ecosystems!
Denitrification
In the final step of the nitrogen cycle, anaerobic bacteria can turn nitrates back into nitrogen gas.
This process, like the process of turning nitrogen gas into ammonia, must happen in the absence of oxygen. As such it often occurs deep in the soil, or in wet environments where mud and muck keep oxygen at bay.
Why is the Nitrogen Cycle Important?
Nitrogen is an essential ingredient for life as we know it. Its unique chemical bonding properties allow it to create structures such as DNA and RNA nucleotides, and the amino acids from which proteins are built. Without nitrogen, these molecules would not be able to exist.
