Power Point Presentation on Nitrogen CyclePower Point Presentation on Nitrogen Cycle- Biology & Chemistry. For School Students.
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Nitrogen fixation refers to the conversion of atmospheric nitrogen gas (N2) to ammonia (NH3) or nitrate (NO3). A few forms of bacteria, life-forms are not able to convert the comparatively inert nitrogen molecule into forms like nitrates and nitrites which can be taken up and used to make the required molecules. These ‘nitrogen-fixing’ bacteria may be free-living or be associated with some species of dicot plants. Most commonly, the nitrogen-fixing bacteria are found in the roots of legumes in special structures called root nodules. Other than these bacteria, the only other manner in which the nitrogen molecule is converted to nitrates and nitrites is by a physical process. During lightning, the high temperatures and pressures created in the air convert nitrogen into oxides of nitrogen. These oxides dissolve in water to give nitric and nitrous acids and fall on land along with rain. These are then utilized by various life forms.
Nitrogen Cycle in an aquarium
The primary source of ammonia (NH3) is created when fish consume food and oxygen (O2) and create waste and carbon dioxide (CO2). The fish waste then decays into ammonia. Other sources include excess food that is not eaten as well as decaying plants and dead fish. The rise in ammonia triggers the growth of Nitrosomonas which produce nitrites (NO2). The nitrites trigger the growth of Nitrospira to produce nitrates (NO3). The nitrates and carbon dioxide are consumed by plant life which produce oxygen through the process of photosynthesis. Excess nitrates are removed by water changes.