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Powerpoint environment
 

Powerpoint environment

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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