Nitrogen Cycle Flashcards
what is the process of mineralization?
When plants and animals die, microorganisms degrade their tissues. These microorganisms convert the complex organic material first into inorganic forms and then into forms that can be then taken up by organisms and converted into living tissue again
what is the significance of plants and what critical role do they play in?
they play a critical role in energy cycling as primary producers
what is a primary producer?
life forms that are able to capture energy from the sun and utilize it to fix atmospheric CO2 into organic carbon.
What are the limiting organic materials in plants?
- Nitrogen
2. phosphorus
Inorganic forms of nitrogen?
- N2 gas
- Ammonia
- Nitrate
- nitrite
Organic forms of nitrogen?
- amino caids
- nucleic acids
- urea
Problem with dinitrogen?
organisms cannot use N2 unless it has been reduced to ammonia (NH3) through nitrogen fixation (reduction)
Examples of natural processes in nitrogen fixation?
Lightning, volcanic eruptions, uv light
2 best way to do nitrogen fixation?
- Soil microbes such as Rhizobium
2. Aquatic forms such as the cyanobacterium Anabaena
Significance of ammonia formed by nitrogen fixation(reduction of nitrogen)?
It serves as a direct/indirect nitrogen source for plants and animals and once absorbed, it can be converted to cellular components such as amino acids, purines, and pyrimidines
2 pathways for the use of ammonia by plants?
- Assimilation of ammonia
2. oxidation of ammonia to nitrate (nitrification) and its subsequent use
What are the two main sources of ammonia in the environment?
- nitrogen fixation
2. ammonification
Explain process of ammonification?
this process is the result of decomposition of dead animals and plants
explain the process of microbial action and their contribution to the release of ammonia?
- microbial action causes the hydrolysis of proteins and nucleic acids, releasing the amino acids and nucleotides
- the nucleotides and amino acids are then further metabolized by microorganisms and the nitrogen released as ammonia
what happens to ammonia produced by microbial action in the soil?
it is mostly absorbed by other microorganisms (very little by plant roots), and then taken into cell material. this is known as ammonia assimilation.