The role of microorganisms in the Nitrogen Cycle Flashcards Preview

F5 Biology C8: Biodiversity > The role of microorganisms in the Nitrogen Cycle > Flashcards

Flashcards in The role of microorganisms in the Nitrogen Cycle Deck (12)
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Why do plants need nitrogen?

To synthesis protein


Plants obtain nitrogen from soil in the form of __________ and __________.

- Nitrate ions NO3-
- Ammonium ions NH4+


Can atmospheric nitrogen be absorbed by plants directly?



What is the function of nitrogen-fixing bacteria?

It is to convert atmospheric nitrogen to ammonium ions via nitrogen-fixing process

N2 ----(nitrogen-fixing process) ----> ammonium ions


State some examples of nitrogen-fixing bacteria.
Where can we find these bacterias?

Rhizobium sp. - linve in the nodules of legumes
Azotobacter sp. - found in soil


State 2 ways of how ammonium ions are release?

1. from nitrogen-fixation process by Rhizobium sp. and Azotobacter sp.

2. from decomposers (bacteria) decomposes dead organisms through ammonification process.


What is ammonification?

Ammonification is the process of decomposers decomposing dead organisms and release ammonium ions (NH4-)


What happens after ammonification?

Ammonium ions are then converted to Nitrite ions (NO2-) by Nitrosomonas sp. via nitrification

After that, nitrite ions (NO2-) will be converted to nitrate ions (NO3-) by Nitrobacter sp.

Then nitrate ions are absorbed by the plants to synthesis protein

Ammonification-----> Nitrification


What other alternative nitrate ions be oxidized?

Lightning in the thunderstorm can oxidise nitrogen to nitrogen dioxide whereby it will dissolve in rain water to form nitrous acid and nitric acid.


What happens to the nitrate ions that are present in the soil?

Excessive nitrate ions will be converted to oxygen gas and nitrogen gas to the atmosphere by denitrification bacteria through denitrification.


How does the denitrification process works?

When excessive nitrate ions in the soils is converted to oxygen gas and nitrogen gas by denitrifying bacteria

Ammonification------> Nitrification -----> Denitrification


Write the equations involve in nitrogen cycle.

N2 + O2 ----> NO2
NO2 +H2O ---> NO2-
NO2- ----> NO3-