13.3- Nutrient cycles

  • Created by: Megan2413
  • Created on: 04-07-17 16:13
State three features of a nutrient sequence
- Nutrients are taken up by producers as simple inorganic molecules - Producers incorporate nutrients into complex organic molecules - Once the producer is eaten the nutrients are passed onto a consumer - Saprobiontic microorganisms break down -->
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complex molecules once producers and consumers die -They then release the simple inorganic molecules into the soil once more to start the cycle again
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Why do living organisms require a source of nitorgen?
To manufacture proteins, nucleic acids and other nitrogen-containing compounds
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As most organisms don't take nitrogen in by gaseous form, how do they take it in?
In the form of nitrate ions from the soil (NO3-)
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By which process do plants take up NO3-?
Active transport via root hair cells
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How do animals obtain nitrogen?
By eating and digesting plants
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Why are nitrate ions so easily leached through the soil?
They are very soluble
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What are the four main stages in the nitrogen cycle?
- Ammonification - Nitrification - Nitrogen fixation - Denitrification
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What is ammonification?
The production of ammonia from organic nitrogen-containing compounds
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Give four examples of nitrogen containing compounds
- Urea - Proteins - Nucleic acids - Vitamins
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How do saprobionts carry out ammonification?
They feed on faeces and dead organisms and release ammonia- forming ammonium ions in the soil
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What is nitrification?
The oxidation reaction that occurs in two stages- converting ammonium ions to nitrite ions to nitrate ions
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Show the equation for nitrification
NH4+ > NO2- > NO3-
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What organism carries out nitrification?
Nitrifying bacteria
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How does farmers ploughing fields help nitrification?
Nitrifying bacteria need oxygen for respiration to oxidise NH4+ to NO3- and ploughing helps aerate the soil and prevent water logging
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What is nitrogen fixation?
A process by which nitrogen in the atmosphere is converted to nitrogen containing compounds
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Which two types of bacteria carry out nitrogen fixation?
- Free living - Mutualistic
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What is released from free living nitrogen fixing bacteria when they die?
Nitrogen-rich compounds
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Where do mutualistic nitrogen fixing bacteria live?
In nodules on the roots of plants (pease, beans)
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What do mutualistic nitrogen fixing bacteria do?
They obtain carbohydrates from the plant which then aquires amino acids from the bacteria
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What is denitrification?
When anaerobic bacteria convert soil nitrates into gaseous nitrogen when the soil isn't aerated and is water logged
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In which form do phosphate ions mainly exist?
As sedimentary rocks
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How are phosphate ions available for absorption from plants from the sedimentary rocks?
When the sedimentary rocks are weathered and eroded
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How do animals recieve phosphate ions?
From eating and digesting plants
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What happens to any excess phosphate ions in animals?
They are excreted and then decomposed by bacteria and fungi, releasing the ions back into water/soil
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How can phosphate ions trapped in bones of animals be returned to the soil or water?
When the animal dies and the bones are eroded
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What happens to phosphate ions that have been run back into streams?
They form sedimentary rocks again
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Card 2

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complex molecules once producers and consumers die -They then release the simple inorganic molecules into the soil once more to start the cycle again

Card 3

Front

Why do living organisms require a source of nitorgen?

Back

Preview of the front of card 3

Card 4

Front

As most organisms don't take nitrogen in by gaseous form, how do they take it in?

Back

Preview of the front of card 4

Card 5

Front

By which process do plants take up NO3-?

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Preview of the front of card 5
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