PMT - Bio 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
• Organisms need the same resources


  They compete for it
• Resources plants may compete for


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


  • Space
  • Food
  • Water
  • Mating partners
• Interdependence


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


  • Birds take shelter in trees
  • Flowers are pollinated with the help of bees
• Removal or addition of a species


  Affects the populations of others greatly
• Stable community


  Where all the biotic (living) and abiotic (non-living) factors are in balance
• As a result the population sizes remain roughly constant
• When they are lost it is very difficult to replace them
• 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


  Structural, behavioural or functional features that allow organisms to survive in their environment
• Structural adaptations


  • Sharp teeth of a carnivore
  • Camouflage
  • Thick layer of fat for insulation
• Behavioural adaptations


  • Playing dead
  • Basking in the sun
  • Courting behaviour
• Functional adaptations


  • Late implantation of embryos
  • Conservation of water through producing little sweat
• 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

  Plants: Curled leaves, extensive root systems, waxy cuticle, water storing tissue
• Food chain


  Feeding relationships shown by a series of organisms where each one feeds on the one below it
• Levels in a food chain


  • Producer
  • Primary consumer
  • Secondary consumer
  • Tertiary consumer
• 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
• Prey population increases


  Predator population also increases
• Not enough prey to feed all predators


  Predator population decreases, allowing prey population to increase again
• Carbon cycle


  The cycling of carbon through an ecosystem
• Carbon cycle


  1. CO2 removed from air in photosynthesis

  2. CO2 returned to air in respiration

  3. CO2 returned to air in combustion
• Water cycle


  The cycling of water through an ecosystem
• Water cycle


  1. Water evaporates from seas and lakes

  2. Water vapour condenses to form clouds

  3. Water returns to land as precipitation

  4. Water runs into seas to repeat the cycle
• Decomposition


  The breakdown of dead organisms and waste by microorganisms
• Factors affecting rate of decomposition

  • Temperature
  • Water
  • Availability of oxygen
• Compost


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


  Produced by anaerobic decomposition of waste, can be burned as fuel
• Biogas generators


  Require constant temperature for microorganisms to respire anaerobically and produce methane
• Investigating effect of temperature on decomposition


  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
• Examples of environmental changes


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