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Basic Sequence of all nutrient cycles
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.
(The names of individual species are not required.…read more

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Nitrogen Fixation
Its when N2 gas in the air is converted into
ammonia by bacteria
The ammonia is used by plants
The relationship is mutualistic- they give the
plants nitrogen compounds and the plants
give them carbohydrates
Nitrogen compounds from
dead organisms (faeces) are
turned into ammonium
compounds by decomposers
Nitrates in soil are
converted into N2
gas by denitrifying
Occurs under
2…read more

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The importance of respiration, photosynthesis and human activity in giving rise to
short term fluctuations and long term change in global carbon dioxide concentration
CO2 is absorbed by plants
during photosynthesis
Carbon is passed onto primary
consumers and along the food
When organisms die the
carbon in them is digested by
Carbon is returned to the air
when decomposers respire
When decomposition cannot
be carried out, carbon
compounds are fossilised. The
carbon in them is released
during combustion.…read more

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The roles of carbon dioxide and methane in enhancing the greenhouse effect and bringing about global warming.
CO2 is a greenhouse gas and may be contributing
to global warming. However the evidence is
correlational, so no definite link can be proven.
The methane concentration has increased
rapidly over the past 50 years.…read more

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Candidates should be able to analyse, interpret and evaluate
data relating to evidence of global warming and its effects on
· the yield of crop plants
· the life-cycles and numbers of insect pests
· the distribution and numbers of wild animals and plants.…read more

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Nitrogen The environmental issues arising from the use of fertilisers.
Leaching and eutrophication.
Leaching is the process where nutrients are removed from the soil. When inorganic fertilisers are
used, minerals are added directly to the soil and are available instantly. As these ions are soluble
they can be carried into nearby waterways by rain water. They may have a harmful effect if the
water source is used for drinking.…read more

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Nutrient Cycles…read more

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Nutrient Cycles…read more


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