Why is n2 unusable

These bacteria use nitrate as an electron acceptor instead of oxygen during respiration. Learning Objectives Describe the nitrogen cycle and how it is affected by human activity. Key Points Nitrogen is converted from atmospheric nitrogen N2 into usable forms, such as NO2-, in a process known as fixation.

The majority of nitrogen is fixed by bacteria, most of which are symbiotic with plants. Recently fixed ammonia is then converted to biologically useful forms by specialized bacteria. This occurs in two steps: first, bacteria convert ammonia in to nitrites NO2-, and then other bacteria species convert it to NO3- nitrate. Nitriates are a form of nitrogen that is usable by plants.

It is assimilated into plant tissue as protein. The nitrogen is passed through the food chain by animals that consume the plants, and then released into the soil by decomposer bacteria when they die. Nitrogen molecules in the atmosphere can also be broken by the energy generated by lightning strikes and volcanic action.

Whenever lightning flashes in the atmosphere, some nitrogen combines with oxygen and forms the gas nitric oxide NO. This nitric oxide is converted to nitric acid, which is highly soluble in water and falls to the ground in rainwater, to be absorbed by soils. Globally, however, nitrogen-fixing bacteria are a far more significant source of fixed nitrogen.

Diagrams demonstrate the creativity required by scientists to use their observations to develop models and to communicate their explanations to others. Students may enjoy experimenting with components of the nitrogen cycle in the student activity, Nitrification and denitrification. Take a closer look at dairy farming and the nitrogen cycle with this article and interactive.

See how nitrogen leaching due to agriculture has increased over time in New Zealand. Add to collection. Nature of science Scientists make observations and develop their explanations using inference, imagination and creativity.

Activity idea Students may enjoy experimenting with components of the nitrogen cycle in the student activity, Nitrification and denitrification. Related content Take a closer look at dairy farming and the nitrogen cycle with this article and interactive. Useful link See how nitrogen leaching due to agriculture has increased over time in New Zealand. Go to full glossary Add 0 items to collection. Download 0 items. Twitter Pinterest Facebook Instagram.

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