The document discusses several nutrient cycles (carbon, water, nitrogen) and how they interact with organisms and the environment. It then covers topics like the human population growth, human influences on ecosystems like agriculture, pollution, and conservation. Specific types of pollution are explained in more detail like water pollution from fertilizers and sewage, air pollution from sulfur dioxide and greenhouse gases, and nuclear fallout from accidents. Agriculture can impact ecosystems through deforestation and fertilizer use.

1. Relationships of organismswithoneanother and withtheirenvironment

3. NUTRIENT CYCLESCarboncycleWatercycleNitrogencycle

4. CARBON CYCLE

6. CARBON CYCLE REMOVAL OF CO₂ FROM THE ATMOSPHEREPHOTOSYNTHESIS: uses light energytoconvert CO₂ intoorganiccompounds in plants.ADDITION OF CO₂ TO THE ATMOSPHERERESPIRATION: 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.

7. WATER CYCLE

9. NITROGEN CYCLE

11. NITROGEN CYCLE1)PROCESSES WHICH ADD NITRATES TO SOILNitrifying 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).

12. 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.

13. 2)PROCESSES WHICH REMONVE NITRATES FROM THE SOILUptakebyplants: plantrootsabsorbnitratesfromthesoil and combine themwiththecarbohydratestomakeproteins.Leaching: as rain waterpassesthroughthesoilitdissolvesthenitrates and carriesthemaway in therun-off ortodeeperlayers of thesoil.Denitrifying bacteria: Theyobtainenergybybreakingdownnitratestonitrogen gas whichthen escapes fromthesoilintotheatmosphere.

14. POPULATION SIZEPOPULATION: group of organisms of onespecies, living in thesamearea at thesame time.

16. HUMAN POPULATION GROWTH

18. HUMAN INFLUENCES ON THE ECOSYSTEMAGRICULTUREPOLLUTIONCONSERVATION

20. POLLUTIONWATER POLLUTION bysewage and chemicalwaste.AIR POLLUTION by: - sulfurdioxide. - greenhouse gases POLLUTION DUE TO PESTICIDES AND HERBICIDES.POLLUTION DUE TO NUCLEAR FALL-OUT

21. 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.

23. AIR POLLUTIONBY 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)

24. Greenhouseeffect:gasescontributing

30. Pollutiondueto nuclear fall-outIONISING RADIATION MAY CAUSE CANCERAccidents at nuclear powerstationsmayreleasesubstancesintotheatmosphere. Exposuretolargeamounts of radiationfromthesesubstances can cause radiationsickness and burns. They can alsoincreasemutationrates in DNA in ourcells, whichmay lead tocancer.Alphaparticles

31. Beta particles

32. Gamma raysAGRICULTUREDEFORESTATIONFERTILISERS