The Nitrogen Cycle - Ecosystems

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Describe decomposition and saprotrophs.
Bacteria and fungi are involved in decomposition. They are saprotrophs and secrete enzymes onto dead or waste material. The enzymes break the material into small molecules which are then absorbed into the organisms body to be stored/respired.
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Nitrogen fixation
Plants cannot use nitrogen directly, need a supply of fixed nitrogen. Occurs when lightning strikes/through Haber process. Nitrogen fixing bacteria e.g. Rhizobium fix nitrogen gas. Live in root nodules e.g. beans, clover. Mutualistic relationship.
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Nitrification
Chemoautotrophic bacteria in the soil absorb ammonium ions. They oxidise ammonium ions to nitrites (Nitrosomonas) and oxidise nitrites to nitrates (Nitrobacter). Oxygen required.
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Denitrification
Bacteria convert nitrates to nitrogen gas. Denitrifying bacteria carry out aerobic respiration.
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Difference between nitrogen fixation and nitrification.
Nitrogen fixation = Nitrogen gas converted into nitrate/ammonium compounds. Nitrification = Conversion of ammonia to nitrate.
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Other cards in this set

Card 2

Front

Plants cannot use nitrogen directly, need a supply of fixed nitrogen. Occurs when lightning strikes/through Haber process. Nitrogen fixing bacteria e.g. Rhizobium fix nitrogen gas. Live in root nodules e.g. beans, clover. Mutualistic relationship.

Back

Nitrogen fixation

Card 3

Front

Chemoautotrophic bacteria in the soil absorb ammonium ions. They oxidise ammonium ions to nitrites (Nitrosomonas) and oxidise nitrites to nitrates (Nitrobacter). Oxygen required.

Back

Preview of the back of card 3

Card 4

Front

Bacteria convert nitrates to nitrogen gas. Denitrifying bacteria carry out aerobic respiration.

Back

Preview of the back of card 4

Card 5

Front

Nitrogen fixation = Nitrogen gas converted into nitrate/ammonium compounds. Nitrification = Conversion of ammonia to nitrate.

Back

Preview of the back of card 5

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