Flashcards
Biology Unit 4 - Nitrogen Cycle
Cards in this deck (15)
- 1What percentage of the air is nitrogen?78%
- 2What is ammonification?The conversion of nitrogen-containing compounds to ammonia (NH4)
- 3What is necessary for ammonification to occur?Saprobiotic micro-organisms
- 4What is nitrification?The conversion of ammonium ions into nitrates
- 5Describe the two steps of nitrification1.Nitrifying bacteria oxidises ammonium ions to nitrites
2.Nitrifying bacteria oxidises nitrites to nitrates - 6What conditions are required for nitrification and why?Abundance of oxygen as it is an oxidation reaction
- 7What is nitrogen fixation?The conversion of nitrogen gas to nitrogen-containing compounds
- 8State the three processes that are responsible for most of the nitrogen-fixation in the biosphere-biological fixation by certain microbes
-atmospheric fixation i.e. lightning
-industrial fixation i.e. Haber Process - 9In what conditions does denitrification occur?Waterlogged soil - lack of O2
- 10What happens during denitrification?Denitrifying bacteria convert and reduce soil nitrates into gaseous nitrogen, leaving the soil deficient in vital nitrates.
- 11What are the two types of fertilisers (giving examples)?-Organic/Natural e.g. animal waste (manure) and bone meal
-Inorganic/Artificial e.g. Nitrogen, phosphorus and potassium are always included - 12What are nitrogen fertilisers used for?To optimise plant growth
- 13What is leaching?Where water-soluble compounds are washed out of the soil by rain or irrigation systems. The nutrients are carried into nearby streams.
- 14What is eutrophication?The build up of nutrients (nitrates and phosphates) in small areas of water e.g. ponds
- 15Briefly describe the steps of eutrophication1.Fertiliser runs into stream
2.Algal bloom due to increased nitrogen
3.Most algae at surface, absorbs light and prevents it from penetrating to lower depths so plants die
4.Saprobiotic micro-organisms grow largely due to dead material in water
5.Saprobiotic micro-organisms use 02 to respire
6.Concentration of O2 decreases in water so aerobic organisms i.e. fish, die
7. Less competition so anaerobic organism populations rise
8.Further decomposition = more nitrates released and some toxic wastes
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- A-Level BIOLOGY A2 Flashcards on Biology Unit 4 - Nitrogen Cycle, created by alice.finlay on 13/10/2015.
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