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


  How organisms in a community depend on other organisms for vital services
• Interdependence examples


  • Birds take shelter in trees
  • Flowers are pollinated with the help of bees
• 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


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


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

  • 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
• Biotic factors that can affect a community

  • Food availability
  • New predators
  • New pathogens
  • Competition
• Adaptation


  Allows organisms to survive in the conditions where they live
• Types of adaptations


  • Structural
  • Behavioural
  • Functional
• Extremophiles


  Organisms that live in environments with extreme conditions
• Examples of 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
• Transect


  Tool used to work out the distribution and abundance of species in an ecosystem
• Quadrat


  Tool 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


  The cycling of carbon through an ecosystem
• Water cycle


  The cycling of water through an ecosystem
• Factors affecting decomposition rate

  • Temperature
  • Water
  • Availability of oxygen
• Compost


  Biological material that has decayed, used as a natural fertiliser
• Methane gas


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

  1. Make a solution of milk and phenolphthalein indicator

  2. Add sodium carbonate to make it alkaline

  3. Place in water bath at specific temperature

  4. Add lipase enzyme and time how long it takes for pink colour to disappear
• Environmental changes affect the distribution of species in an ecosystem
• Examples of environmental changes

  • Temperature changes
  • Water availability changes
  • Atmospheric gas composition changes
• Biodiversity


  The variety of different species of organisms on Earth or within an ecosystem
• High biodiversity means the ecosystem will be stable
• Many human activities are having a negative effect on biodiversity
• Examples of human activities negatively affecting 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