3.4.6 Nutrient Cycles (AQA A2 Biology)

Overview of nutrient cycles for A2 biology. Includes the carbon cycle, greenhouse gases, global warming, nitrogen cycle (ammonification, nitrification, nitrogen fixation and denitrification and the bacterias involved in each process), fertilisers, leaching and eutrophication.

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Page 1

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.


NUTRIENT CYCLES
The role of microorganisms in the carbon and nitrogen cycles in sufficient
detail to illustrate the processes of saprobiotic nutrition,
ammonification, nitrification, nitrogen fixation and denitrification.




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Page 2

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.


THE CARBON CYCLE
The importance of respiration, photosynthesis and human activity in
giving rise to short-term fluctuations and long-term change in global
carbon dioxide concentration.
The roles of carbon dioxide and methane in enhancing…

Page 3

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.



GLOBAL WARMING and DEFORESTATION

Reasons for deforestation:
Mining
Agriculture
Fuel demand
Raw materials
Transport routes

Impact on ecosystem
Reduced species diversity: Many species live in forests, they will die.
Water cycle: Trees keep water…

Page 4

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.


The environmental issues arising from the use of fertilisers.
Leaching and eutrophication.

Plants need nitrogen to grow but must get this through nitrate ions in
the soil which are taken in by root hair…

Page 5

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.


In intensively farmed areas of land, natural minerals and ions are in constant demand
due to farmers wanting to gain maximum yield from their crops. However, very few
ions are recycled back into the…

Page 6

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3.4.6 Chemical elements are recycled in ecosystems. Microorganisms play a
key role in recycling these elements.


1. Nitrates are a limiting factor for the growth of plants in water.
2. Nitrates leach into the water, plants and algae grow quickly.
3. Algal bloom appears.
4. Light can't penetrate past the…

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