Energy and ecosystems Flashcards
Step one and two and 2of the phosphorous cycle
- Weather and erosion of rocks cause phosphate ions to dissolve and so available for plants to absorb and incorporate into their biomass
- P ions passed onto animals which feed on to plants.
- Excess p ions are excreted and accumulate in waste material
Step 4 and 5 of the P cycle
- Animals and plants die, decomposers break them down and release P ions into the soil or water
- p ions in excretion, dissolved from rocks, released by decomposers are then transported by streams into oceans and lakes where they form sedimentary rocks and completes the cycle
Adaptation of Mycorrhizae in nutrient cycles
They act like extensions of the plant root system and so increase SA for the uptake of water and minerals
How does Mycorrhizae help in cycles
Act like a sponge and hold water and mineral ions together in the roots so the plant better resists drought and increased uptake of iorganic ions
How is mycorrhizae mutualistic
They help plants improve water and inorganic uptake while fungus receives organic compounds from plants
How do fertilisers increase productivity
Nitrogen needed in amino acids, ate and nucleotides for plant growth. If nitrate ions readily available then plants start to develop earlier, increase SA and leaf size, This increase rate of PS and improves crop productivity
Give me an effect of nitrogen containing fertilisers
Reduced species diversity-
Nitrogen rich soils favour the growth of gaseous/other rapid growing species and these outcompete other species so die as a result
Explain what leeching is
Rainwater will dissolve any soluble nutrients and carry them deep into the soil like beyond the roots. The leached nitrate ions will then go into streams and rivers
- Harmful effect if its a drinking source fore animals and humans
- increased N2 conc harmful as can cause eutrophication
Explain the first few steps of eutrophication
Caused by leechig
- usually low conc of nitrate ions so its a limiting factor for plant and algaue
- leeching causes increase conc of nitrate ions so no longer limiting factor and plants and algae start to grow
- Algae mostly grow on the surface so becomes densely populated and causes algal bloom
- So absorbs light and prevents light from penetrating to lower depths, so plants an algae lower don’t have enough light for growth and eventually die
Explain second part of eutrophication
- sapriobiots used dead organisms as food and grow. They require o2 for respiration so increased demand for o2
- Conc of o2 decreased and nitrates are released from decaying organisms
- o2 then becomes a limiting factor and aerobic organisms eventually die
- less comp of anaerobic organisms so pop increases and they further decompose dead material and so release more pirates and toxic wastes
What are the four stages of the nitrogen cycle
- Ammonification
- Nitrification
- Nitrogen fixation
- Denitrification
Explain ammonification
Conversion of ammonia from organic nitrogen containing compounds
like urea, protein, nucleic acids.
Saprobionts feed on feaces and so realease ammonia. Forms ammonium ions in the soil and nitrogen return to non-living components of the ecosystem
Nitrification
Conversion of ammonium ions into nitrate ions
Oxidation reactions by nitrifying bacteria
- Ammonium ions oxidation to nitrite ions
- oxidation of nitrite ions to nitrate ions
Rewuires o2
Nitrogen fixation
Conversion of nitrogen gas into nitrogen contains compounds
- free living nitrogen fixing bacteria. Reduce gaseous nitrogen into ammonia and used to manufacture amino acids
- mutualist nitrogen fixing bacteria
live on the nodules of roots of plants
obtain carbohydrates from plants and plants acquire amino acids from bacteria
Denitrification
Soil becomes waterlogged so conc of o2 decreases.This changes species so less aerobic nitrifying bacteria and more anaerobic denitrifying bacteria. These convert soil nitrates into gasous nitrogen so reduce availably of nitrogen contains compounds for plants
