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29 Cards in this Set
- Front
- Back
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Define extinction |
The complete loss of a species |
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Causes of extinction |
1. Natural selection due to changing selection pressures 2. Non-contiguous populations are populations with insufficient genetic diversity to support a health population 3. Loss of habitat e.g. due to deforestation 4. Over hunting by humans e.g. fishing 5. Competition from invasive species (interspecific competition) 6. Pollution from humans e.g. oil |
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Define conservation |
Conservation is the protection, preservation, management and restoration or natural habitats and their ecological communities |
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The aim of conservation |
To maintain species and genetic biodiversity while allowing human activity to continue |
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Ways to achieve conservation |
1. Protecting habitats (nature reserves) 2. Trade restrictions (on endangered species and their parts e.g. ivory) 3. Gene and sperm banks 4. Seed banks (Kew gardens) 5. Rare species societies 6. Species reintroduction (red kites in Wales) 7. International organisation (e.g. WWFN aims to educate and increase public awareness) 8. Legislation 9. Ecotourism (educates and contributes to local economies) |
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Why is maintaining biodiversity of species and alleles essential |
May be used for future medicines or to help crop growth. Some alleles may provide selective advantages to species to prevent extinction. Ethics - each species and their combination of genes is unique and precious |
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Agricultural exploitation |
Intensive farming has led to an increase in the use of chemical fertilisers, herbicides and insecticides. Large machinery also requires larger spaces meaning many hedgerows have been lost to make room. Hedgerows are a key habitat so this reduces biodiversity. These larger fields are used to grow monocultures (lots of the same plant e.g. wheat). Monocultures provide the same habitat which reduces biodiversity. They also reduce soil fertility due to roots growing the same and taking the same nutrients, this increases the need for chemical fertilisers. Additionally, plants of the same species grown so closely together are at risk of pests and disease which can spread rapidly, on mass. This increases the need for pesticides. |
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Monoculture |
The growth of large numbers of genetically identical crop plants in a defined area |
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Overgrazing |
Overgrazing land can lead to compacted soil with reduced air spaces. This inhibits the nitrogen cycle, reducing soil fertility. Water is also unable to penetrate compacted soil and grass growth is limited |
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Future farming |
Organic farming - reducing the use of chemical fertilisers and pesticides. Growing different crops to provide varied habitats and a greater biodiversity Set-aside schemes - farmers set aside land for conservation and wildlife. Government grants make up for loss of earnings Legislation - increased number of hedgerows, increasing biodiversity |
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Deforestation |
The complete loss of trees due to human activity in a defined area. The land is then used for farming, building or infrastructure. Trees are being cut down faster than they can regenerate. |
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Consequences of deforestation |
Soil erosion Lowland flooding Desertification Habitat loss Decrease in biodiversity Climate change |
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Forest management |
Woodlands are important resources. Managed forestry involves sustainable replanting and regeneration. Methods include: -Coppicing (cutting trees leaving a stump so shoots can grow. These can grow and be cut at different diameters for different purposes e.g. building or fencing. Coppiced woods offer a variety of habitats and increase biodiversity) -Selective cutting -Long rotation time Good forest practice includes planting trees optimum distances apart, controlling the spread of pests and disease, controlled timber cutting and the protection of native woodlands |
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Overfishing |
Overfishing depletes fish stocks. Populations may become too low to recover. This affects food chains and entire ecosystems. Commercial fishing methods: 1. Drift netting - a net stretched between 2 boats which often catch non-target species e.g. dolphins 2. Trawling - a weighted net is dragged along the ocean floor, catching everything and damaging the ocean floor, destroying habitats for many miles |
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How to preserve natural fish stocks |
Regulating mesh size Quotas and landing size regulations Exclusion zones Legislation limiting the size of fishing fleets and controlling the number of days at sea Fishing alternative species Using lines not nets |
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Fish farming |
Fish farming is large-scale, intensive farming where fish are bred and mature in enclosed ponds. Food, predation, disease and parasites are controlled. Warm water used to accelerate growth. Disadvantages include: -rapid spread of disease and parasites due to high density populations (this can be controlled by antibiotics and pesticides which can then enter the food chain) -pesticides bioaccumulate and can cause infertility to species at higher trophic levels -nitrogenous waste pollution leading to eutrophication -escaped farmed fish are larger and may outcompete wild fish for resources. They may also carry disease and parasites to wild populations -farmed fish e.g. salmon contain high levels of toxic chemicals such as pesticides |
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Monitoring for sustainability |
Monitoring is used to determine the quality of an environment. Factors that can be monitored: -air quality -soil quality -water quality |
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Environmental impact assessments |
Environmental impact assessments are used to evaluate proposed projects. They include: -description of the site and of the project -description of biotic and abiotic factors -mitigation, looking at ways to limit environmental damage and maintaining biodiversity |
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Planetary boundaries |
The planetary boundaries define the safe operating space for humanity - if all 9 are exceeded, earth may no longer be able to support a human population |
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What are the 9 planetary boundaries? |
1. Climate change 2. Biosphere integrity 3. Land system change 4. Biogeochemical flow 5. Ozone depletion in the stratosphere 6. Ocean acidification 7. Fresh water use 8. Atmospheric aerosols 9. Introduction of new entities |
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Climate change boundary |
Disruption of the carbon cycle due to combustion, deforestation and decomposition |
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Biosphere integrity boundary |
Human activity introduces new section pressures which decrease biodiversity |
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Land system change boundary |
The balance between protection of habitats and human needs |
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Biogeochemical flow boundary |
Disruption of the nitrogen cycle due to inhibition of nitrogen fixing and nitrification and denitrification. Eutrophication due to nitrogen pollution in pathways |
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The Ozone depletion in the stratosphere boundary |
Ultraviolet light causes CFCs to release as chlorine as free radicals which break down ozone. The reduction in CFCs globally has reversed the depletion of the ozone |
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Ocean acidification boundary |
Carbon dioxide dissolves in water as hydrogen carbonate, releasing hydrogen ions which causes acidification and a decrease in pH. Fish gills damaged by low pH. |
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Fresh water use boundary |
All organisms need regular access to fresh water e.g. ice caps, lakes, streams. Climate change and chemical pollution may limit freshwater sources |
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The atmospheric aerosol boundary |
Aerosols are microscopic particles released in the atmosphere by the combustion of fuels and mining. These particles cause respiratory problems and reduce photosynthesis (leaves covered in particles) |
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Introduction of new entities boundary |
Organic pollutants, radioactive materials, nano-materials and plastic included. Some chemicals are so toxic they are banned e.g. PCBs |
