1. Aim: to explore the carbon and nitrogen cyclesObjectives Describe how energy flows in an ecosystem Illustrate the carbon and nitrogen cycles Explain how human activity is affecting carbonemissions

2. Trophic Levels Energy moves from one organisms to anotherwhen it is eaten Each step in this transfer of energy is known as atrophic level The main trophic levels are producers and consumers 3. Food Chains The energy flow from one trophic level to the other is know as a food chain A simple food chain shows how energy istransferred from the sun through living organisms. It involves one organism at each trophic level Producers (e.g. plants) Primary Consumers Secondary Consumers Tertiary Consumers 4. Food Chain 5. Food Web Most animals eat more than JUST one organism So in any ecosystem food chains connect to form afood web Food webs are more complex and involve lots oforganisms 6. Food web Identify trophic levels 7. Ecological Pyramid At each trophic level energy is used and waste materialproduced So there is less energy available for transfer at eachstage and a food pyramid is formed 8. Carbon cycle 9. AtmosphericCarbon Dioxide 10. Atmospheric Carbon DioxidePlants use carbondioxide to make theirfood (photosynthesis) 11. Atmospheric Carbon DioxidePlants use carbondioxide to make theirfood (photosynthesis)Green plants areeaten by animals 12. AtmosphericCarbon Dioxide respirationPlants use carbondioxide to make theirfood (photosynthesis) Green plants are eaten by animals 13. Atmospheric Carbon Dioxide respirationPlants use carbondioxide to make theirfood (photosynthesis) green plants are eaten by animals dead remains of plants and animals 14. AtmosphericCarbon DioxiderespirationPlants use carbondioxide to make theirfood (photosynthesisgreen plants areeaten by animalsdead remains of plantsand animals decay by fungi and bacteria 15. Plants use carbon Carbon is pulled from the atmosphere by plants and used for the process of photosynthesis used to make organic molecules (carbohydrate, proteinsand fats) The carbon becomes part of the plant (stored food). 16. Animals eat plants When organisms eat plants, they digest the organic compounds and use these products for their own purposes. All leaving organisms carry out respiration breaking down food substances to release energy. This also produces carbon dioxide which returns to the atmosphere. 17. When plants and animals die, most of their bodies are decomposed by fungi and bacteria. They break down organic compounds via respiration to carbon dioxide and carbon atoms are returned to the atmosphere. Some are not decomposed fully and end up in deposits underground (oil, coal, etc.). Humans burn these fuels releasing carbon dioxide into the atmosphere. 18. Carbon Cycle Diagram Carbon in AtmosphereDecomposersbreak down dead Plants use carbonthings, releasing to make foodcarbon toatmosphere andPlants and soil animals die Fossil fuels are Animals eatburned; carbon plants and takeis returned to Bodies not in carbon atmospheredecomposed Carbon slowly after manyreleased from theseyears, become part substances returns of oil or coal to atmospheredeposits 19. Carbon in Oceans Additional carbon is stored in the ocean. Many animals pull carbon from water to use inshells, etc. Animals die and carbon substances aredeposited at the bottom of the ocean. Oceans contain earths largest store of carbon. 20. Human Impact Fossil fuels release carbon stores very slowly Burning anything releases more carbon intoatmosphere especially fossil fuels Increased carbon dioxide in atmosphere increasesglobal warming Fewer plants mean less CO2 removed fromatmosphere 21. Greenhouse Gases The greenhouse effect is causing the Earth to warm up. This is causing climate change and melting of the polar ice caps, this It is due to increasing could lead to flooding. amounts of greenhouse gases, such as carbon Burning fuels is a dioxide, water vapour and major cause of this methane.increase. Video 22. Nitrogen cycle 23. Nitrogen (N2) in atmosphere Amino acids Assimilation and proteins inplants and animalsNitrogen by plantsfixationDenitrifying bacteriaDetritusNitrogen-fixingbacteria in rootNitratesnodules of legumes (NO3)Detritivores Nitrogen-fixingDecompositionbacteria in soilNitrogenfixation Ammonium (NH4+) 24. The largest single source of nitrogen is in the atmosphere.Nitrogen (N2) makes up 79% ofour air!But living organisms cannot usethis form directly 25. There are 4 phases in the cycle: Nitrogen fixation = NH3/NH4+ Decay = decomposing organic nitrogen into NH4+ Nitrification = converting NH4+ to NO2 to NO3 Denitrification = converting NO3 into N2Micro-organisms play an important part in this cycle! 26. Nitrogen Fixation The enormous energy of lightning breaks nitrogen moleculesapart and enables the nitrogen atoms to combine withoxygen forming nitrogen oxides (N2O) Nitrogen oxides dissolve in rain, forming nitrates (NO3) Nitrates (NO3) are carried to the ground with the rain. N N O(N2O)(NO3) 27. Lightning fixes Nitrogen!NN O Nitrogen combineswith OxygenNitrogen oxides forms(N2O) Nitrogen oxidesdissolve in rain and(NO3) change to nitratesPlants use nitrates togrow! 28. Industrial FixationNNH Under great pressure, at aN H3 temperature of 600Industrial Plant combines C, and with the use of anitrogen and hydrogen catalyst, atmospheric nitrogen (N2) and hydrogen are combinedAmmonia is formed to form ammonia (NH3). (NH3) Ammonia can be used as a fertiliser.Ammonia is used as a fertilizer in soil 29. Biological Fixation Some bacteria, including Rhizobium, live in the soil or within root nodules of legumes (peas, beans and clover) These bacteria are anaerobic and use enzymes to convert nitrogen gas (N2) to ammonium ions (NH4+) The plants supply the bacteria with energy and nutrients in return of nitrogen fixation (mutualism) 30. Symbiotic RelationshipLegume plantsBacteriaBacteria live in the roots ofNlegume family plants andprovide the plants withammonium (NH4) in exchangeNH3for the plants carbon and aprotected home.NRoots with noduleswhere bacteria liveNitrogen changes intoammonium 31. Decay Animals acquire their amino acids when they eat plants. When animals and plants die their remains are used asfood by micro-organisms such as bacteria and fungi. Decomposers convert the nitrogen back into ammonia(NH3)Decomposers convert organic nitrogento ammonia (NH3) Ammonia (NH3) is used by some plants Ammonia (NH3) is stored in soil. 32. Nitrification Living in the soil are nitrifying bacteria. First, Nitrosomonas bacteria combine ammonia with oxygen toform nitrites. Then another group of nitrifying bacteria, Nitrobacter, convertnitrites to nitrates which green plants can absorb and use!Nitrifying bacteria in soil combineammonia with oxygenAmmonia changes to nitritesNitrifying bacteria in soil convert Nitratesnitrites to nitratesAmmonia Nitrites (NH3) (NO2) (NO3) Plants absorb nitrates and grow! 33. ATMOSPHEREN2 Amino acids N2Nitrogen-fixing bacteria NH4+ Soil NH4+ NO3 (ammonium)(nitrate)Nitrifyingbacteria Ammonifying bacteriaOrganicmaterial RootFigure 32.13 34. Denitrification Denitrification converts nitrates (NO3) in the soil to atmospheric nitrogen (N2) which is returned to the air. Denitrifying bacteria live deep in soil and in aquatic sediments where conditions make it difficult for them to get oxygenDenitrifying bacteria live (NO3) (N2)deep in soil and usenitrates as an alternativeNitrogen into oxygen making aatmosphere closes thebyproduct of nitrogen gas.nitrogen cycle! 35. Acid RainHuman activity have doubledthe amount of fixed nitrogenentering the nitrogen cycle injust 100 yearsManufacture and use ofnitrogenfertilisers, combustion of Climate change, acid fossil fuels and forest rain, the acidification of burning soils and loss of soil nutrients, and the acidification of streams and lakes.Kills fish, damages trees and buildings.Video