Topic 7 : 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, resulting in population sizes remaining 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
• Biogas generator

  Used to produce methane, requires constant temperature
• Investigating the effects of temperature on decay

  1. Make milk and phenolphthalein solution

  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
• 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
• Humans have only recently tried to reduce their impact on biodiversity