Ecology and Biodiversity
IGCSE (Year 10โ11) ๐ฟ Ecology & Evolution Ecosystems, nutrient cycles, biodiversity, conservation.
๐ Ecosystems and Biodiversity
An ecosystem includes all living organisms (biotic factors) and their abiotic (non-living) environment in an area.
- Population โ all individuals of the same species in an area at the same time
- Community โ all populations of all species in the same area
- Ecosystem โ community + abiotic environment
- Biodiversity โ variety of species, genetic diversity within species, and diversity of ecosystems
- Threats to biodiversity: habitat destruction, overexploitation, invasive species, pollution, climate change
๐ Nutrient Cycles
Matter is recycled continuously through ecosystems by nutrient cycles.
Carbon Cycle โ key processes
Photosynthesis (COโ โ organic carbon) โท Respiration (organic carbon โ COโ)Decomposition โ COโ released. Combustion of fossil fuels โ COโ released.
Nitrogen Cycle โ key steps
Nโ fixation (Rhizobium in root nodules) โ NHโ/NHโโบNitrification (Nitrosomonas) โ NOโโป โ NOโโป (Nitrobacter)
Plants absorb NOโโป โ amino acids โ proteins โ eaten by animals
Decomposers โ ammonification โ NHโ
Denitrification (Pseudomonas) โ Nโ released back to atmosphere
๐ Human Impact
- Deforestation โ removes carbon sink, destroys habitats, increases soil erosion, disrupts water cycle
- Eutrophication โ agricultural runoff (nitrates/phosphates) โ algal bloom โ decomposers use up Oโ โ aquatic organisms die
- Climate change โ COโ and methane trap heat (greenhouse effect) โ habitat loss, species extinction, altered food webs
- Conservation methods: national parks, seed banks, captive breeding, international agreements, marine protected areas
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Interactive Demo โ Ecology and Biodiversity
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