Question

explain nitrogen cycle long ans​

Answer 1

• 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.

Answer 2

Answer:

Nitrogen Cycle Steps

The basic steps of the nitrogen cycle are illustrated here:

Nitrogen Cycle Steps

Nitrogen Cycle Steps

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.

Interestingly, the enzyme nitrogenase can only function when oxygen isn’t present. As a result, organisms that use it have had to develop oxygen-free compartments in which to perform their nitrogen fixation!

Common examples of such nitrogen-free compartment sare the Rhizobium nodules found in the roots of nitrogen-fixing legume plants. The hard casing of these nodules keeps oxygen out of the pockets where Rhizobium bacteria do their valuable work of converting nitrogen gas into ammonia.

You can see the oxygen-free Rhizobium nodules, visible as big round lumps, on the roots of this cowpea plant:

Rhizobia nodules on Vigna unguiculata

Rhizobia nodules on Vigna unguiculata

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.

These bacteria don’t convert ammonia for plants and animals out of the goodness of their hearts. Rather, they are “chemotrophs” who obtain their energy from volatile chemicals. By metabolizing nitrogen along with oxygen, they obtain energy to power their own life processes.

The process can be thought of as a rough (and much less efficient) analog to the cellular respiration performed by animals, which extract energy from carbon-hydrogen bonds and use oxygen as the electron acceptor, yielding carbon dioxide at the end of the process.