Nitrogen Fixation
This is the chemical formula for the gas form of nitrogen found in our atmosphere, which cannot be used directly by most living things.
What is N2?
This molecule, released during ammonification, is the starting material that nitrifying bacteria convert during nitrification.
What is ammonium (NH4+)?
Besides amino acids, this is the other type of molecule, essential for storing genetic information, that plants build using assimilated nitrogen.
What are nucleic acids (DNA/RNA)?
This general term describes the organisms, bacteria and fungi, responsible for breaking down organic matter and waste into ammonium during ammonification.
What are decomposers?
This is the general term for bacteria that use nitrate instead of oxygen to carry out respiration in low-oxygen soils and water.
What are denitrifying bacteria?
This natural, non-biological source of nitrogen fixation occurs when electrical energy splits atmospheric N2 and O2, allowing them to combine into nitrates that fall to Earth in rain.
What is lightning (abiotic fixation)?
This describes the type of soil environment (rich or poor in a certain gas) that nitrification requires to occur.
What is oxygen-rich / aerobic?
These are the two inorganic forms of nitrogen that plant roots absorb from the soil.
What are nitrate (NO3-) and ammonium (NH4+)?
Besides dead organisms, ammonification also breaks down nitrogen-rich waste products, such as this compound found in animal urine, back into ammonium.
What is urea (or uric acid)?
In the first step of denitrification, anaerobic bacteria reduce nitrate into this compound instead of using oxygen for respiration.
What is nitrite (NO2-)?
This human-made industrial process combines nitrogen and hydrogen gas under high heat and pressure to mass-produce ammonia, mainly for fertilizer.
What is the Haber-Bosch process?
Name both genera of bacteria responsible for the two steps of nitrification: one converts ammonium to nitrite, the other converts nitrite to nitrate.
What are Nitrosomonas and Nitrobacter?
In plant cells, absorbed nitrate must first be reduced to this intermediate compound before being converted into ammonia and used to build amino acids and nucleic acids.
What is nitrite (NO2-)?
These are the two general sources of organic nitrogen that decomposers break down during ammonification, releasing ammonium into the soil.
What are dead organisms and animal waste (excretion)?
This is the greenhouse gas intermediate produced partway through denitrification, before the final enzyme converts it into harmless dinitrogen gas.
What is nitrous oxide (N2O)?