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Sources: Jones, IGCSE Biology- Mackean, IGCSE Biology - Pickering, Complete Biology

Sources: Jones, IGCSE Biology- Mackean, IGCSE Biology - Pickering, Complete Biology

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Powerpoint environment Powerpoint environment Presentation Transcript

  • Relationships of organismswithoneanother and withtheirenvironment
  • NUTRIENT CYCLES
    Carboncycle
    Watercycle
    Nitrogencycle
  • CARBON CYCLE
  • CARBON CYCLE
    REMOVAL OF CO₂ FROM THE ATMOSPHERE
    PHOTOSYNTHESIS: uses light energytoconvert CO₂ intoorganiccompounds in plants.
    ADDITION OF CO₂ TO THE ATMOSPHERE
    RESPIRATION: convertscarbohydratestoCO₂ withtherelease of energy.
    DEATH AND DECAY: provideplant and animal material fordecomposers – bacteria and fungi.
    COMBUSTION: releasesCO₂ bytheburning of fossilfuels.
    FOSSILISATION:Thehydrocarbonfuels, such as coal and petroleum, come fromancientplantswhichhaveonlypartlydecomposedoverthemillion of yearssincetheywereburied.
  • WATER CYCLE
  • NITROGEN CYCLE
  • NITROGEN CYCLE
    1)PROCESSES WHICH ADD NITRATES TO SOIL
    Nitrifying bacteria: they use ammoniafronexcretoryproducts and decayingorganisms as a source of energy. In thisprocessthey produce nitrates.
    Thereis a specialgroup, thenitrogen-fixing bacteria, which can absorb N₂ as a gas fromthe air spaces in thesoil, and builditintocompounds of ammonia, which can beeasilybechangedtonitratesbyothernitrifying bacteria. Some of theselive in therootsnodulesofleguminousplants(peas,beans, clover).
  • 1)PROCESSES WHICH ADD NITRATES TO SOIL(cont)
    Lightning: lightningdischargesmakessome of thenitrogen gas in the air combine withoxygen, formingnitrogen oxides. Theydissolve in rain, and are washedintothesoil, wheretheyformnitrates.
  • 2)PROCESSES WHICH REMONVE NITRATES FROM THE SOIL
    Uptakebyplants: plantrootsabsorbnitratesfromthesoil and combine themwiththecarbohydratestomakeproteins.
    Leaching: as rain waterpassesthroughthesoilitdissolvesthenitrates and carriesthemaway in therun-off ortodeeperlayers of thesoil.
    Denitrifying bacteria: Theyobtainenergybybreakingdownnitratestonitrogen gas whichthen escapes fromthesoilintotheatmosphere.
  • POPULATION SIZE
    POPULATION: group of organisms of onespecies, living in thesamearea at thesame time.
  • HUMAN POPULATION GROWTH
  • HUMAN INFLUENCES ON THE ECOSYSTEM
    AGRICULTURE
    POLLUTION
    CONSERVATION
  • POLLUTION
    WATER POLLUTION bysewage and chemicalwaste.
    AIR POLLUTION by: - sulfurdioxide.
    - greenhouse gases
    POLLUTION DUE TO PESTICIDES AND HERBICIDES.
    POLLUTION DUE TO NUCLEAR FALL-OUT
  • POLLUTION OF WATER: the 2 pollutantsthat reduce oxygen in water are:
    Fertilisers: nitrates and phosphates are addedtothesoilbyfarmers. Some are washedfromthesoilby rain intothenearestpond, lakeorriver. Thisprocessiscalledleaching.
    Sewage: containsanexcellentsource of organicfoodfrom bacteria, and alsocontainsphosphatesfromdetergents.
  • AIR POLLUTION
    BY SULFUR DIOXIDE: contributestoacid rain.
    BY GREENHOUSE GASES CONTIBUTING TO GLOBAL WARMING.
    Carbon + O₂ -> carbonmonoxide (CO)
    and carbondioxide (CO₂)
    Sulphur + O₂ -> sulphurdioxide (SO₂)
    Nitrogen + O₂ -> nitrogenmonoxide (NO)
    and nitrogendioxide (NO₂)
  • Greenhouseeffect:gasescontributing
  • Pollutiondueto nuclear fall-out
    IONISING RADIATION MAY CAUSE CANCER
    Accidents at nuclear powerstationsmayreleasesubstancesintotheatmosphere. Exposuretolargeamounts of radiationfromthesesubstances can cause radiationsickness and burns. They can alsoincreasemutationrates in DNA in ourcells, whichmay lead tocancer.
    • Alphaparticles
    • Beta particles
    • Gamma rays
  • AGRICULTURE
    DEFORESTATION
    FERTILISERS