The Nitrogen Cycle - Ecosystems - Flashcards in A Level and IB Biology

Created by: Steff06
Created on: 03-02-16 12:27

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

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

Card 4

Front

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

Back

Card 5

Front

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

Back

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The Nitrogen Cycle - Ecosystems