Week 3: Food Webs and Trophic Cascades Flashcards
Matter is?
Conserved
List the 3 abiotic factors
- Atmosphere
- Hydrosphere
- Lithosphere
Biogeochemical cycles describe…
The way CHNOPS (carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur) move through both abiotic and biotic (biosphere) factors
List the 5 biogeochemical cycles
- Water cycle
- Carbon cycle
- Nitrogen cycle
- Phosphorus cycle
- Sulfur cycle
Nitrogen and phosphorus are known as what?
Limiting nutrients - they are critical for life
Where is most nitrogen found?
In the atmosphere as N2 (gaseous)
How is this unusable N2 converted to usable nitrogen?
Via nitrogen fixation by bacteria. N2 –> NH3 (ammonia)
Describe what happens to ammonia (fixed nitrogen) after it is assimilated by plants and animals?
Death and decay occurs and NH3 undergoes ammonification –> NH4+ (ammonium) due to the works of bacteria and fungi (decomposers)
What occurs after ammonification?
Other bacteria and fungi cause nitrification - NH4+ is converted into nitrites (NO2-) and nitrates (NO3-)
How does this nitrogen then return to the atmosphere?
Denitrifying bacteria cause the nitrogen to return to the atmosphere
Name the 2 ways phosphorus enters the cycle?
- Weathering and erosion
2. Fertiliser application
Describe the phosphorus cycle?
Assimilation occurs followed by death and decay, P then runs off and enters the water supply (as phosphate) making its way to the oceans where it settles and forms sedimentary rock that then are uplifted and the cycle begins again
List 3 ways in which sulfur enters the atmosphere
- As dimethyl sulfide from bacteria
- Factories and industrial means from fossil fuels
- Volcanoes as hydrogen sulfide
List 3 ways in which sulfur enters the atmosphere
- As dimethyl sulfide from bacteria
- Factories and industrial means from fossil fuels
- Volcanoes as hydrogen sulfide
