Nutrient Cycling Flashcards
What 3 things do ecosystems require to remain sustainable?
1) Continuous energy supply (i.e: light)
2) Nutrient cycling
3) Recycling of waste
What is a biochemical cycle
the cycling of nutrients via biological, geological and chemical pathways
Name 3 examples of biochemical cycles
Any from: • Carbon - (carbon cycle) • Nitrogen - (nitrogen cycle) • Oxygen - (oxygen cycle) • Phosphorus - (phosphorus cycle) • Sulphur - (sulphur cycle) • Water - (hydrological cycle)
Which 4 gases make up 96% of cells?
Carbon
Oxygen
Hydrogen
Nitrogen
Which are the 2 main types of biochemical cycles?
Gaseous
Sedimentary
Which 4 biochemical cycles are gaseous?
Carbon
Oxygen
Sulphur
Nitrogen
Which 4 biochemical cycles are sedimentary?
Phosphorus
Potassium
Calcium
Iron
What 2 phases are involved in sedimentary cycles?
Solution phase - where weathering releases minerals from parent rocks, that dissolve as salts in the sea
Rock phase - These salts are deposited out as sediment and rock in shallow seas
What % of the atmosphere is nitrogen?
80%
Why is nitrogen in the atmosphere difficult for plants to use?
Because most is locked up as N2(g) which cannot be used
Why is nitrogen important for life forms?
It is critical for DNA, protein, chlorophyll and ATP
which 4 sources do plants obtain nitrogen from?
1) Nitrate fertilisers, ammonia or manure in soil
2) Decomposing organic matter
3) Nitrogen fixation during natural processes like lightening
4) Biological Nitrogen Fixation (BNF)
What 4 transformations does Nitrogen undergo during the nitrogen cycle?
1) Biological nitrogen fixation
2) Nitrification
3) Denitrification
4) Ammonification
Name 2 ways nitrogen can exist organically
Amino acids
Nucleic acid
Name 2 ways nitrogen can exist inorganically
Ammonia
Nitrate
Which type of enzyme is needed for BNF?
nitrogenase enzymes
Name 3 bacteria that nitrogenase enzymes can be found in
1) Aquatic cyanobacteria
2) free-living soil bacteria - i.e: Azobacter
3) Symbiotic bacteria in association with legume plants - i.e: Rhizobium
What do nitrogenase enzyme containing bacteria do to nitrogen in BNF?
They convert nitrogen to ammonia (so it becomes fixed)
Which type of bacteria is most important in biological nitrogen fixation?
Symbiotic bacteria
What is nitrification?
The conversion of ammonia to nitrate
Is biological nitrogen fixation an anaerobic or aerobic process?
Anaerobic - enzymes don’t need oxygen
Is nitrification an anaerobic or aerobic process?
Aerobic - does require oxygen
What are the 2 steps in nitrification?
1) ammonia oxidation
2) nitrite oxidation
Which type of bacteria converts ammonia ions to nitrite in nitrification?
nitrosomonas bacteria
Which type of bacteria converts nitrite to nitrate in the second stage of nitrification ?
Nitrobacteria
Where does ammonia come from?
Fish waste and urine
decaying plant matter
Excess fish food
Fertilizers
Briefly describe the process of nitrification
nitrosomonas bacteria consume ammonia ions and convert it into nitrite. Then nitrobacteria consume the nitrite and convert it into nitrate
What is denitrification?
When nitrate is converted into nitrogen gas and returned to the atmosphere
Is denitrification an anaerobic or aerobic process?
Anaerobic - no O2 needed
Where does denitrification occur?
In soil, sediment, anoxic zones of lakes and oceans
Why is denitrification important?
Reduces the risk of water causing pollution - i.e: algal blooms
What is ammonification?
When ammonia is produced through organism waste or decaying dead matter
How does ammonification release nitrogen into the ecosystem?
Decomposers (fungi and bacteria) break down organic matter, releasing nitrogen from DNA and amino acids as ammonia
What is the organic form of nitrogen?
Ammonia
What type of nitrogen fixation converts more nitrogen to ammonia than the whole biosphere?
Industrial fixation
What is the main impact of fertilisers on ecosystems?
Eutrophication
Briefly describe how eutrophication is problematic
Excess nitrogen from fertilisers seep into ground water.
Heavy rain runs it into rivers and streams.
Nitrogen causes rapid growth of algae.
When algae dies, it decreases dissolved O2 levels in water causing mass mortality of aquatic organisms
Briefly describe the 4 steps of the carbon cycle
1) Carbon enters atmosphere as CO2 from RESPIRATION and COMBUSTION
2) CO2 is used up in photosynthesis
3) Consumers feed on plants, passing carbon up the food chain.
4) Animals die, decomposers break down organic matter, releasing CO2 by respiration
Name 2 fossil fuels
Oil
Coal
Methane?
How does burning fossil fuels release carbon?
Carbon is sometimes trapped in dead organisms.
These organisms fossilise in rock.
When burned, the carbon is released along with water and energy.
The carbon is returned back to the atmosphere by CO2
what is Rhizobium
soil bacteria that fix nitrogen - found in legume roots
what is Azotobacter
A free-living soil bacteria that fixes nitrogen
