Nitrogen Cycle Flashcards
1
Q
What do nutrient cycle rely on to break down organic molecules into simple inorganic molecules and ions?
A
Sapriobionts
2
Q
- What are the characteristics of Nitrogen gas?
A
- triple covalent bond
- air is 78% nitrogen
3
Q
What are sapriobionts ?
A
microorganisms (fungi/bacteria) that live on dead/decaying organisms
4
Q
How do sapriobionts feed?
A
- extracellular digestion: by secreting digestive enzymes
- absorb soluble nutrients released
- convert organic into inorganic compounds
5
Q
What is an example of saprobionts converting larger organic molecules into inorganic compounds?
A
DNA, RNA ‒> phosphate and nitrates
6
Q
What are the 4 main parts of the nutrient cycle?
A
- Nitrogen fixation
- Ammonification
- Nitrification (oxidation)
- Denitrification
7
Q
What occurs during Nitrogen Fixation?
A
- converting nitrogen gas into a nitrogen containing compound
- This can be done in the root nodules of a Legume Plant as there is nitrogen fixing bacteria which converts atmospheric nitrogen into ammonium (symbiotic relationship)
- Plants without nodules
- nitrogen fixing bacteria in the soil which react nitrogen in atmosphere converting it into ammonium
8
Q
What occurs in Nitrification?
A
- The ammonium created needs to be nitrifyed before it can be absorbed
- Ammonium ions in the soil are oxidised into nitrites by nitfriying bacteria and further into nitrates
- 2 stage oxidation reaction
9
Q
What occurs in assimilation?
A
- Those nitrates which can be disolved are absorbed by active trabnsport and are used to create amino acids, ATP, DNA etc
- animals eat plants > nitrates absorbed
- waste produced (urea) and animals eventually die
10
Q
What part do saprobionts play to digest and breakdown proteins?
A
- The organic Nitrogen for decompoistion of DNA, proteins and urea which is done my sapriobionts
- This is known as ammonification.
- DNA, RNA -> ammonia
11
Q
What occurs in denitrification?
A
- Denitrification bacteria can convert nitrates back into nitrogen gas in the atmosphere.
- limiting process: as nitrogen gas cannot be absorbed by plants
12
Q
What causes denitrification?
A
- Soils with limited oxygen in waterlogged areas
- carried out by anaerobic denitrifying bacteria
