Biology - 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


  Where all the biotic (living) and abiotic (non-living) factors are in balance, so 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
• Types of adaptations


  • Structural
  • Behavioural
  • Functional
• Extremophiles


  Organisms that live in environments with extreme conditions like high temperatures, pressures or salt concentrations
• 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 (usually a green plant or algae) 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 and returned to the air through respiration and combustion
• Water cycle


  Water evaporates, forms clouds, and returns to land as precipitation
• 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
• Environmental changes like temperature, water availability, and atmospheric gas composition can 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
• Many human activities are having a negative effect on biodiversity
• Ways human activities negatively impact biodiversity

  • Destroying habitats

  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
• Peat bogs are being destroyed – they are being drained in order to create space for farming, peat is used as compost, or dried to use as fuel as it contain carbon (releasing CO2 into the atmosphere)
• Peat is being used up quicker than it is being formed, as the formation process is slow