Question

examples of biological N fixation that occur in the Pacific Northwest region. Please address these questions:

• What is biological nitrogen fixation?

• Why is the fixation process important?

• What is symbiosis? Who does what, and how do they benefit?

• What is nitrogenase? What is leghemoglobin?

• What is the role of molybdenum and iron in biological nitrogen fixation?

• What is inoculation?

Answer 1

1. Reduction of atmospheric nitrogen to ammonia by living organisms is called biological nitrogen fixation.

2. Nitrogen is required for the synthesis proteins, but plants can not utilize atmospheric nitrogen. Only some prokaryotic organisms can help in incorporation of the atmospheric nitrogen into plant tissues. Because of this process, plants can grow in nitrogen poor soil.

3. Symbiosis is a mutually beneficial association between two organisms in which both the organisma are benefitted from the association.In biological nitrogen fixation, symbiosis occurs between leguminous plants and Rhizobium bacteria which resides into the root nodules of leguminous plants.  

Because of this mutualistic association, the plants get nitrogen in the form of ammonia which they use for the synthesis of amino acids and proteins. Bacteria in return, get shelter and prepared food from the plant.

4. Nitrogenase is an enzyme which catalyses the conversion of atmospheric N₂ to NH_{3 .}

Nitrogenase enzyme is sensitive to molecular oxygen. It needs oxygen free environment for catalytic activity.   Leghaemoglobin, a pinkish pigment acts as oxygen scavenger by combining rapidly with oxygen like haemoglobin.

5. Molybdenum and iron are components of nitrogenase enzyme.

6. Inoculation is the act of introducing microorganisms in a culture medium. In leguminous plants, specially when first time it is sown, inoculation is done to ensure nitrogen fixation.