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Hope Raybould



The Environment and
Ecosystems
Biology AS




Hope Raybould
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Key Terms
Biosphere- the part of the earth and atmosphere that is inhabited by living organisms

Ecosystems- The living world and its inhabitants. Consists of communities of organisms
which interact with each other and their physical and chemical environments.

Habitat- place where organisms live.

Biodiversity- the number and range of…

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Pyramids of number, biomass
And energy
Show the relationship between trophic levels

Pyramids of number
Width of each block is proportional to numbers of organisms
present at each trophic level i.e. the number of snails

Advantages-

data is easy to collect by straightforward sampling
methods

Disadvantages-

Difficult to draw pyramid…

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Advantages-

Rate of production taken into account. Each bar shows amount of energy per unit area
flowing through trophic level at given time.
Inverted pyramids can't be obtained.
Input of solar energy can be included at base
Weight for weight; two species may not have same energy content so biomass…

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Humans disrupt carbon cycle by burning fossil fuel, cutting down forest and burning wood to release
CO2 from sinks back into the atmosphere.


Nitrogen Cycle

Putrification- the
conversion of
inorganic nitrogen
into ammonia



Nitrification- the
conversion of
ammonia into
nitrites and then
nitrates



Nitrogen
fixation-
conversion of
atmospheric
nitrogen into…

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Energy Resources
Burning fossil fuels causes concerns about-

Environmental impact- carbon dioxide produced, increases greenhouse effect, acid rain, oil
pollution
Sustanability- length of time which they will last, non-renewable resources.
Centrilisation into areas or companies- major sources of energy may become unavailable
outside region for political reasons

Coal

Formed from…

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Energy from Renewable Biomass
Wood and animal dung may be used as biomass
Energy is extracted by direct burning with air in a boiler to provide steam to turn turbines
Energy plantations use fast growing woody species with short rotation coppicing. Fast
growing; easy to propagate and give high yields.…

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Deforestation
Forests are exploited for-

Timber and fuelwood
Mineral
Extraction of medecines
Food
Rood built through forests
Paper
Provide land for crops/livestock

Effects of deforestation-

Less carbon dioxide taken out of atmosphere as less tress
Microbial population in soil is upset as organic matter is washed away
Soil loses its…

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HOWEVER additional pressure from increase in human population results in wider areas being
used for grazing and gathering
These demands exceed carrying capacity of land; vegetation can't recover unless pressure is
removed.
LACK OF VEGETATION = DESERTIFICATION

Effects of lack of vegetation-

Deterioration of land and soil
Desiccation and erosion…

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Evidence of same in Canada, USA, Scotland and Wales
Add lime to neutralise acid




Loss of phytoplankton, water becomes more transparent-less microscopic material in
suspension.
Effects food chain, some species more abundant and others are lost
pH of below 4.5 trout can't produce enzyme to break out of eggs so…

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