Karteikarten
The Nitrogen Cycle
Karten in diesem Stapel (8)
- 1Why is Nitrogen important?Nitrogen and phosphorus is needed in order to make other vital compounds. It is also needed for growth.
Nitrogen gas makes up 80% of the atmosphere - produces can only absorb it in the form of nitrate ions - 2What are the 3 main stages in the production of nitrates from proteins?1. Saprobiotic digestion - digestion of proteins to amino acids by decomposers; this digestion involves hydrolysis, catalysed by enzymes
2. Ammonification - formation of ammonium compounds from amino acids
3. Nitrification - conversion of ammonium compounds to nitrates - 3What is Ammonification?Following decomposition the metabolism of many bacteria results in nitrogen-containing amino groups being removed from amino acids converting them into ammonia or ammonium ions.
- 4What is Nitrification?The process that converts ammonium ions into nitrate ions - carried out by nitrifying bacteria. This is carried out in two stages:
Ammonia-> Nitrites-> Nitrates
These are oxidation reaction-which release energy-the nitrifying bacteria use this energy to synthesis their own organic compounds - chemosynthesis - 5What is Denitrification?When there is no oxygen available (eg, waterlogged fields) denitrifying bacteria use nitrate ions instead of oxygen as the final electron acceptors during respiration. This produces nitrogen gas which is released into the atmosphere - reducing the amount of nitrates in the soil
- 6What is Nitrogen fixation?When atmospheric Nitrogen is converted into ammonia by Nitrogen-fixing bacteria.
Nitrogen is combined with hydrogen ions obtained from water.
Some of these nitrogen-fixing bacteria live freely in the soil or water but others can only fix nitrogen when living inside leguminous plants
E.g., Rhizobium Bacteria have nitrogenase enzymes that fix nitrogen and produce ammonia, this is then converted into amino groups that are used to synthesise amino acids. - 7What are Mycorrhizae ?'Fungus-roots'
The threads of mycorrhizae grow in and around the roots giving them a much greater surface area - 8Why is mycorrhizae an example of mutualism?Both species (mycorrhizae and the plants) benefit
The plant benefits from the increased surface area as this increases absorption of water and minerals. They are also able to absorb minerals more efficiently due to different membrane proteins and absorption mechanisms
The mycorrhizae benefits from the sugars that the plant provides.
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- Beschreibung
- A level Biology (Nutrient cycles) Karteikarten am The Nitrogen Cycle, erstellt von Tia Lander am 25/03/2017.
- Erstellt von
- Tia Lander
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