nutrient cycles Flashcards
step 1 of the phosphorus cycle
phosphorus in rocks is released into the soil to form phosphate ions by weathering
step 2 of the phosphorus cycle
phosphate ions are taken up from the soil by plants or absorbed by algae in the water by absorption
step 3 of the phosphorus cycle
(consumption)
phosphate ions are transferred to consumers by feeding up the food chain
step 4 of the phosphorus cycle
phosphate ions in waste products and dead organisms are released into the soil during decomposition by saprobionts
step 5 of the phosphorus cycle
phosphate ions are taken up and trapped in sediments
what is the main reservoir of phosphorus
rocks, in the form of phosphate ions
what is mycorrhizae
fungi which allows for a symbiotic relationships between fungi and plant root systems of most plants making the plants drought - resistant
what is hyphae
long filaments which make up fungi which increase the surface area, increasing the absorption of water and mineral ions
use of phosphorus
nucleic acids, ATP + phospholipids. in the form of phosphate ions
what is the use of fertilisers
replace lost minerals increasing the efficiency of energy transfers
what are natural fertilisers
organic matter e.g. manure and compost
what are artificial fertilisers
inorganic matter e.g. chemicals
pros and cons of fertilisers
+ increases yield of plants
- eutrophication
pros and cons of natural fertilisers
+ less likely to burn the plants
+ improves soil quality
+ cheaper
-takes longer for results
- cant control nutrients it contains
pros and cons of artificial fertilisers
+ faster results
+ control of the nutrients provided
- can burn the plants
- stricter application method
-expensive
what do all fertilisers contain
Nitrogen, Phosphorus and Potassium (NPK fertilisers)
how does eutrophication occur
when nitrates are leached into lakes and rivers
what is leaching
when water soluble compounds are washed away into rivers or ponds
step 1 of eutrophication
mineral ions are leached from fertilised fields, and the stimulation growth of algae in ponds and rivers
step 2 of eutrophication
excessive growth of algae forms an algal bloom, blocking light
step 3 of eutrophication
this means plants cant photosynthesis so die
step 4 of eutrophication
saprobionts will feed on the dead matter. the increased number of bacteria, reduced conc of oxygen by respiring
step 5 of eutrophication
aquatic organisms will die due to the lack of dissolved oxygen
how are nutrients lost from the soil
crops take in minerals from the soil, when they are harvested the minerals are not returned to the soil in a nutrient cycle.
importance of the nitrogen cycle
recycles nitrogen for proteins, DNA and RNA
what is the main reservoir of nitrogen
the atmosphere - 78% nitrogen gas
what does the nitrogen cycle do
turns nitrogen gas into different forms organisms can use
what are the 4 steps of the nitrogen cycle
nitrogen fixation
ammonification
nitrification
denitrification
what is nitrogen fixation
converting nitrogen gas into nitrogen containing compounds
what occurs during nitrogen fixation
mutualistic bacteria in the root nodules of legumes fix N2 into NH3
nitrogen fixing bacteria in the soil fix N2 into ammonia and used to make amino acids
what is ammonification
converting nitrogen - containing compounds into ammonia or ammonium
what occurs during ammonification
1.death and excretion of organisms release urea and proteins (which contain nitrogen)
2.saprobionts decompose them into NH4+
3. NH4+ is absorbed and assimilated by plants
what is nitrification
NH3 and NH4+ are oxidised into nitrites then nitrates
what occurs during nitrification
nitrifying bacteria oxidise NH3 and NH4+ into NO2-
NO2- is further oxidised into NO3-
what is denitrification
converting NH3 back into N2
what occurs during denitrification
NH3 is converted into N2 by denitrifying bacteria which are anaerobic.
when does denitrification occur
in anaerobic conditions, when the soil is water logged where there is not enough oxygen in the soil as it has been displaced by water
