Read the following passage carefully and answer the following questions:
Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules
essential to life like many proteins ,nucleic acids(DNA and RNA) and some vitamins and also
found in many biologically important compounds such as alkaloids and urea. Nitrogen is thus an
essential nutrient for all life forms. However, other than a few forms of bacteria ,all life forms
are not able to convert the inert nitrogen molecule into forms like nitrates and nitrites which
can be taken up and used to make the required molecules.
a) Name two organisms , which play vital role in nitrogen fixation?
b) Why is nitrogen fixing bacteria are found only in roots of leguminous plants?
c) Write the name of two processes involved in cycling of nitrogen in the environment?
Nitrogen gas makes up 78% of our atmosphere and nitrogen is also a part of many molecules
essential to life like many proteins ,nucleic acids(DNA and RNA) and some vitamins and also
found in many biologically important compounds such as alkaloids and urea. Nitrogen is thus an
essential nutrient for all life forms. However, other than a few forms of bacteria ,all life forms
are not able to convert the inert nitrogen molecule into forms like nitrates and nitrites which
can be taken up and used to make the required molecules.
a) Name two organisms , which play vital role in nitrogen fixation?
b) Why is nitrogen fixing bacteria are found only in roots of leguminous plants?
c) Write the name of two processes involved in cycling of nitrogen in the environment?
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Answer:
a) rhizobium bacteria and blue green algae
b) Because rhizobium bacteria is found in only leguminous plant roots
c) nitrogen fixation and nitrification
1. The two organisms which play vital role in nitrogen fixation are:
(i) Rhizobium (bacteria) and Blue green Algae—fixationof free atmospheric nitrogen into ammonia. (ii) Nitrosomonas (nitrifyingbacteria) convert ammonia to nitrites and Nitrobactor convert nitrites into nitrates.
2. Legumes use nitrogen fixing bacteria, specifically symbiotic rhizobia bacteria, within their root nodules to counter the limitation. ... The plant root cells convert sugar into organic acids which then supply to the rhizobia in exchange, hence a symbiotic relationship between rhizobia and the legumes.
3. The conversion of nitrogen can be carried out through both biological and physicalprocesses. Important processes in thenitrogen cycle include fixation, ammonification, nitrification, and denitrification. The majority of Earth'satmosphere (78%) is atmospheric nitrogen, making it the largest source of nitrogen.