Ecology

• Community


  Many different populations interact in the same habitat
• Ecosystem


  The interaction of a community with non-living (abiotic) parts of the environment
• Organisms


  • Adapted to live in the conditions of their environment
• Competition


  Can be within a species or between different species
• Things plants may compete for

  • Light
  • Space
  • Water
  • Mineral ions
• Things animals may compete for

  • Space
  • Food
  • Water
  • Mating partners
• Interdependence


  Organisms in a community depend on other organisms for vital services like food, shelter and reproduction
• The removal or addition of a species to the community can affect the populations of others greatly, as it changes prey or predator numbers
• Stable community


  All the biotic (living) and abiotic (non-living) factors are in balance, so population sizes remain roughly constant
• Abiotic factor


  A non-living factor that can affect a community
• Abiotic factors


  • Light intensity
  • Temperature
  • Moisture levels
  • Soil pH and mineral content
  • Wind intensity and direction
  • Carbon dioxide levels
  • Oxygen levels for aquatic animals
• Biotic factor


  A living factor that can affect a community
• Biotic factors


  • Food availability
  • New predators
  • New pathogens
  • Competition
• Adaptations


  • Structural
  • Behavioural
  • Functional
• Extremophiles


  Organisms that live in environments with extreme conditions
• Adaptations for different scenarios

  • Cold climates: Smaller surface area to volume ratio, lots of insulation
  • Dry climates: Adaptations to kidneys, active in early morning/evening, larger surface area ratio
  • Plant adaptations: Curled leaves, extensive root systems, waxy cuticle, water storing tissue
• Producer


  Photosynthetic organisms that make glucose through photosynthesis
• Primary consumer


  Organisms that eat the producers
• Secondary consumer


  Organisms that eat the primary consumers
• Tertiary consumer


  Organisms that eat the secondary consumers
• Transects and quadrats


  Tools used to work out the distribution and abundance of species in an ecosystem
• A stable community will show population cycles between the predators and prey
• Carbon cycle


  CO2 is removed from the air in photosynthesis, returned to the air in respiration and combustion
• Water cycle


  Water evaporates, forms clouds, precipitates, and runs into seas to repeat the cycle
• Factors affecting decomposition rate

  • Temperature
  • Water
  • Availability of oxygen
• Compost


  Produced when biological material decays, used as a natural fertiliser
• Methane gas


  Produced by microorganisms decomposing waste anaerobically, can be burnt as a fuel
• Investigating effects of temperature on decay

  Make milk and phenolphthalein solution, add sodium carbonate, place in water bath, add lipase enzyme, time how long it takes for pink colour to disappear
• Environmental changes affect the distribution of species in an ecosystem
• Biodiversity


  The variety of different species of organisms on Earth or within an ecosystem
• High biodiversity means the ecosystem will be stable</b>
• Many human activities are having a negative effect on biodiversity
• The future of humans on Earth depends on maintaining biodiversity
• Human activities negatively impacting biodiversity

  • Using more land for houses, farming, shops, roads and factories
  • Pollution (sewage, fertiliser, toxic chemicals, smoke, acidic gases)
  • Using up raw materials quicker than they are being produced
• The future of humans on Earth depends on maintaining biodiversity – for example for food and new medicines
• The impact of our activities is getting bigger as the population is increasing, as more resources are being used and more waste is being produced
• Negative human impacts on ecosystems

  • More land is being used for houses, farming, shops, roads and factories, which destroys habitats
  • Pollution kills plants and animals
  • Sewage, fertiliser and toxic chemicals pollute the water
  • Smoke and acidic gases pollute the air
  • Landfill and toxic chemicals can result in the pollution of the land
  • We are using up raw materials quicker than they are being produced
• Humans have only recently tried to reduce their impact
• Peat


  A material that forms when plant material has not fully decayed as there is not enough oxygen
• Peat bogs


  • They accumulate in acidic and waterlogged areas
  • They are a habitat for many species, in particular for migrating birds