Environment Revision

Hopefully useful for anyone studying biology, made for the old sylabus so not all of it may be relevant.

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  • Created by: Hope
  • Created on: 19-11-08 15:09
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Hope Raybould
The Environment and
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 organisms in a given area
Producers- organisms that are able to synthesis complex organic substances from
onorganic substances such as carbon dioxide and water.…read more

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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
data is easy to collect by straightforward sampling
Difficult to draw pyramid to scale due to range of numbers
True pyramids not often obtained as producers vary in size; often get inverted pyramid
(like left)
Inverted pyramid, one oak tree can feed a hundred caterpillars...…read more

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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 may be
misleading.…read more

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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.…read more

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Energy Resources
Burning fossil fuels causes concerns about-
Environmental impact- carbon dioxide produced, increases greenhouse effect, acid rain, oil
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
Formed from vegetation that accumulates in peat bogs in waterlogged, anaerobic conditions. Gets
buried and compacted, turns into hard rock (lithification)
Aneorobic decomposition of organic material (animals/fish).…read more

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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.
They are coppiced (cut down to near ground) at end of first year and crop of wood is taken 2
to 5 years later from side shoots.
Can benefit wildlife by providing habitats for them.…read more

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Forests are exploited for-
Timber and fuelwood
Extraction of medecines
Rood built through forests
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 roughness and surface run off increases as trees and vegetation usually retain
Soil and nutrients washed into rivers and streams meaning soil poor in nutrients
Nutrients lost and taken away
Natural nutrient cycle taken…read more

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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.…read more

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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
Effects food chain, some species more abundant and others are lost
pH of below 4.…read more


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