Carbon and nitrogen cycle

1. Carbon and Nitrogen Cycle

2. Aim: to explore the carbon and nitrogen cycles Objectives Describe how energy flows in an ecosystem Illustrate the carbon and nitrogen cycles Explain how human activity is affecting carbon emissions

3. Trophic Levels Energy moves from one organisms to another when it is eaten Each step in this transfer of energy is known as a trophic level The main trophic levels are producers and consumers

4. 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 is transferred from the sun through living organisms . It involves one organism at each trophic level Producers (e.g. plants) Primary Consumers Secondary Consumers Tertiary Consumers

5. Food Chain

6. Food Web Most animals eat more than JUST one organism So in any ecosystem food chains connect to form a food web Food webs are more complex and involve lots of organisms

7. Food web Identify trophic levels

8. Ecological Pyramid At each trophic level energy is used and waste material produced So there is less energy available for transfer at each stage and a food pyramid is formed

9. Carbon cycle

10. Atmospheric Carbon Dioxide

11. Atmospheric Carbon Dioxide P lants use carbon dioxide to make their food ( photosynthesis )

12. Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food ( photosynthesis ) Green plants are eaten by animals

13. Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food ( photosynthesis ) Green plants are eaten by animals respiration

14. Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food ( photosynthesis ) green plants are eaten by animals respiration dead remains of plants and animals

15. Atmospheric Carbon Dioxide Plants use carbon dioxide to make their food ( photosynthesis green plants are eaten by animals respiration dead remains of plants and animals decay by fungi and bacteria

16. Plants use carbon Carbon is pulled from the atmosphere by plants and used for the process of photosynthesis used to make organic molecules (carbohydrate, proteins and fats) The carbon becomes part of the plant (stored food).

17. 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.

18. 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.

19. Carbon Cycle Diagram Carbon in Atmosphere Plants use carbon to make food Animals eat plants and take in carbon Plants and animals die Decomposers break down dead things, releasing carbon to atmosphere and soil Bodies not decomposed — after many years, become part of oil or coal deposits Fossil fuels are burned; carbon is returned to atmosphere Carbon slowly released from these substances returns to atmosphere

20. Carbon in Oceans Additional carbon is stored in the ocean. Many animals pull carbon from water to use in shells, etc. Animals die and carbon substances are deposited at the bottom of the ocean. Oceans contain earth’s largest store of carbon.

21. Human Impact Fossil fuels release carbon stores very slowly Burning anything releases more carbon into atmosphere — especially fossil fuels Increased carbon dioxide in atmosphere increases global warming Fewer plants mean less CO 2 removed from atmosphere

22. 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 could lead to flooding. It is due to increasing amounts of greenhouse gases, such as carbon dioxide, water vapour and methane. Burning fuels is a major cause of this increase. Video

23. Nitrogen cycle

24. Denitrifying bacteria Nitrates (NO 3 – ) Detritivores Ammonium (NH 4 + ) Amino acids and proteins in plants and animals Detritus Assimilation by plants Nitrogen-fixing bacteria in soil Nitrogen fixation Decomposition Nitrogen-fixing bacteria in root nodules of legumes Nitrogen fixation Nitrogen (N 2 ) in atmosphere

25. The largest single source of nitrogen is in the atmosphere . Nitrogen (N2) makes up 79% of our air ! But living organisms cannot use this form directly

26. There are 4 phases in the cycle: Nitrogen fixation = NH3 / NH 4 + Decay = decomposing organic nitrogen into NH 4 + Nitrification = converting NH 4 + to NO 2 to NO 3 Denitrification = converting NO 3 into N 2 Micro-organisms play an important part in this cycle!

27. Nitrogen Fixation The enormous energy of lightning breaks nitrogen molecules apart and enables the nitrogen atoms to combine with oxygen forming nitrogen oxides (N 2 O) Nitrogen oxides dissolve in rain, forming nitrates ( NO 3 ) Nitrates (NO 3 ) are carried to the ground with the rain. N N O (NO 3 ) (N 2 O)

28. Lightning “fixes” Nitrogen ! Nitrogen combines with Oxygen Nitrogen oxides forms Nitrogen oxides dissolve in rain and change to nitrates Plants use nitrates to grow! (NO 3 ) N N O (N 2 O)

29. Industrial Plant combines nitrogen and hydrogen Ammonia is formed Ammonia is used as a fertilizer in soil (NH 3 ) N N H N H 3 Industrial Fixation Under great pressure, at a temperature of 600 ºC, and with the use of a catalyst, atmospheric nitrogen (N 2 ) and hydrogen are combined to form ammonia (NH3) . Ammonia can be used as a fertiliser .

30. 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 (NH 4 + ) The plants supply the bacteria with energy and nutrients in return of nitrogen fixation (mutualism) Biological Fixation

31. Legume plants Roots with nodules where bacteria live Nitrogen changes into ammonium NH 3 N N Symbiotic Relationship Bacteria Bacteria live in the roots of legume family plants and provide the plants with ammonium (NH 4 ) in exchange for the plant’s carbon and a protected home.

32. Decay Animals acquire their amino acids when they eat plants. When animals and plants die their remains are used as food by micro-organisms such as bacteria and fungi. Decomposers convert the nitrogen back into ammonia (NH3) Ammonia ( NH 3 ) is stored in soil. Decomposers convert organic nitrogen to ammonia ( NH 3 ) Ammonia ( NH 3 ) is used by some plants

33. Nitrifying bacteria in soil combine ammonia with oxygen Ammonia changes to nitrites Nitrifying bacteria in soil convert nitrites to nitrates Plants absorb nitrates and grow! Ammonia Nitrites Nitrates (NH 3 ) (NO 3 ) (NO 2 ) Nitrification Living in the soil are nitrifying bacteria. First, Nitrosomonas bacteria combine ammonia with oxygen to form nitrites . Then another group of nitrifying bacteria, Nitrobacter , convert nitrites to nitrates which green plants can absorb and use !

34. Figure 32.13 ATMOSPHERE N 2 N 2 Nitrogen-fixing bacteria Ammonifying bacteria Organic material NH 4 + (ammonium) Nitrifying bacteria NO 3 – (nitrate) Root NH 4 + Amino acids Soil

35. Denitrification Denitrification converts nitrates (NO 3 ) in the soil to atmospheric nitrogen (N 2 ) 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 oxygen Denitrifying bacteria live deep in soil and use nitrates as an alternative to oxygen making a byproduct of nitrogen gas. Nitrogen in atmosphere closes the nitrogen cycle! (NO 3 ) (N 2 )

36. Acid Rain Human activity have doubled the amount of fixed nitrogen entering the nitrogen cycle in just 100 years Manufacture and use of nitrogen fertilisers, combustion of fossil fuels and forest burning Kills fish, damages trees and buildings. Video Climate change, acid rain, the acidification of soils and loss of soil nutrients, and the acidification of streams and lakes.