How is the nitrogen cycle important to humans?
it produces free nitrogen that humans can breathe.
it converts nitrogen into a form that humans can obtain by eating other organisms.
it produces nitrogen compounds that humans can breathe.
it converts nitrogen into a form that humans can obtain by absorbing it through their skin.

It converts nitrogen into a form that humans can obtain by eating other organisms.

The nitrogen cycle involves the transition of different forms of nitrogen. This is facilitated by different species interaction in an ecosystem. The organisms convert nitrogen into forms readily used by them. Nitrogen is essential for the synthesis of amino acids and nucleotides in all living species. Nitrogen cycle involves four main steps: fixation, nitrification, ammonification and de-nitrification.

Fixation: In this process the nitrogen dioxide from the atmosphere is fixed by the nitrogen fixing bacteria present in the soil. These bacteria have nitrogenase enzyme that combines nitrogen with hydrogen to produce ammonia. These bacteria remains in the symbiotic association with the roots of the plants. The ammonia is taken up by the plant to prepare proteins.

Nitrification: Some plants are not able to take up ammonia , nitrate is another form of nitrogen can be utilized by the plants for their growth.The nitrification process converts the ammonia into nitrate. It is performed by the bacteria nitrobactor.

Ammonification: In ammonification, bacteria or fungi converts the organic nitrogen from dead remains of plants and animals into ammonia.

De-nitrification: Nitrogen in it's nitrate form is converted back into atmospheric nitrogen form by some bacterial species.

Nitrogen cycle is necessary for humans because humans are dependent upon other organism for their food and energy requirements. They obtain their food from plants and animals. The plants receives nitrogen in the form of nitrates and ammonia which are necessary for synthesis of amino acids, further required for protein synthesis. Proteins are building blocks of life. Proteins helps in the growth of plants. These plants are eaten up by humans and herbivores like goat, sheep. Some of these herbivores are eaten up by humans.

Therefore, nitrogen cycle is important for humans because it converts nitrogen into a form that humans can obtain by eating other organisms.

The answer is B. It converts nitrogen into a form that humans can obtain by eating other organisms.

a. decomposes use carbon from dead organisms as fuel for cellular respiration, returning carbon dioxide back into the atmosphere.

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