Cycles

Nitrogen cycle Nitrogen is required by all living organisms Why? Plants obtain nitrogen from either nitrate or ammonium ions What's the chemical formulae for nitrate, nitrite and ammonium ions?

Draw the nitrogen cycle

50% fertilizer (Bacteria)

Micro-organisms involved in the Nitrogen cycle Nitrosomonas Nitrobacter

Denitrifying bacteria Under anaerobic conditions (waterlogged soils), denitrifying bacteria convert nitrate to nitrite and then to nitrogen gas Pseudomonas denitrificans and Thiobacillus denitrificans are denitrifying bacteria

Nitrogen fixation Nitrogen fixation results in the production of ammonia from nitrogen and ammonia Ammonia is produced by lightning. Ammonia can also be produced by the Haber- Bosch process, using an iron-based catalyst, very high pressures and fairly high temperature. Major conversion of nitrogen into ammonia is achieved by micro-organisms in the process called nitrogen fixation

What’s the chemical equation for the Haber process?

Biological nitrogen fixation Azotobacter vinelandii are free living micro- organisms in the soil, that fix nitrogen Root nodules occur where Rhizobium form a mutualistic relationship with a plant How is the above relationship mutualistic?

How can humans disrupt this cycle?

Ideas Addition of vast quantities of fertiliser Dumping of raw sewage Excess nitrate in water leads to eutrophication Waterlogged soils undergo more denitrification releasing nitrous oxide –a greenhouse gas.

Draw the carbon cycle

15%/year CO 2 & CH 4

Carbon cycle What human activities contribute to an increase in carbon dioxide emissions into the atmosphere? Why is an increase in atmospheric carbon dioxide potentially dangerous?

Quiz answers Photosynthesis Nitrobacter/ Nitrosomonas Nitrogen gas Nitrogen to ammonia Combustion To build organic molecules-proteins/nucleic acids By burning fossil fuels

cont 8-any 3 Glucose, starch, fat, protein 10- Haber process/ by bacteria 11-An organism that produces organic compounds from inorganic materials 12- fungi and bacteria

Summary The nitrogen cycle is comprised of several important micro-organisms that convert nitrogen into accessible forms for other organisms to use (heterotrophic consumption) The carbon cycle involves build up of organic materials in living organisms and their release and breakdown to carbon dioxide in the environment Plants reduce carbon dioxide levels in the atmosphere Human activities can lead to disruptions on the nitrogen and carbon cycles

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