7 - ecology

• habitat - place organism lives
• population - all organisms of one species living in a habitat
• community - populations of different species living in a habitat
• abiotic factors - non-living factors of environment, eg. temperature
• biotic factors - living factors of environment, eg. food
• ecosystem - interaction of a community of living organisms with non-living parts of their environment
• animals compete for space, food, water and mates
• plants compete for light, space, water and mineral ions
• interdependence - each species depends on other species for things like food, shelter, pollination and seed dispersal
• stable community - where species and environmental factors are in balance so population sizes are roughly constant eg. tropical rainforest and old oak woodlands
• abiotic factors:

  • moisture
  • light intensity
  • temperature
  • CO2 level
  • wind intensity and direction
  • O2 level
  • soil pH and mineral content
• biotic factors:

  • new predators
  • competition
  • new pathogens
  • availability of food
• structural adaptations:

  organism's body shape or colour

  • colour - camouflage
  • blubber, low sa:v to retain heat
  • thin layer of fat, large sa:v to lose heat
• behavioural adaptations:

  • migration
• functional adaptations:

  inside the body

  • producing little sweat, little concentrated urine
  • hibernation - lower metabolism
• extremophiles - adapted to live in extreme conditions, eg. temperature, salt concentrations, and pressure
• biomass - mass of living material/energy stored
• energy is transferred through living organisms in an ecosystem when they are eaten
• population may be limited by food available
• predator-prey cycles are always out of phase because it takes a while for one population to respond to changes in the other
• organisms live in different places because the environment varies
• distribution - where an organism is found
• studying distribution:

  • measure how common an organism is in two sample areas using quadrates and compare them
  • study how distribution changes across an area, using quadrates along a transect

  quantitative data
• quadrats:

  • place on ground at random point
  • count organisms in quadrat
  • repeat
  • work out mean number of organisms per quadrat
  • repeat in second sample area
  • compare means
• transects:

  • mark out a line with a tape measure
  • collect data along line (count organisms that touch line) or (place quadrates next to each other or at intervals)
• estimate percentage cover by counting squares for organisms like grass
• availability of water changes in seasons
• environmental changes like water, temperature and atmospheric gases can be caused by seasonal factors, geographic factors or human interaction
• water cycle:

  • energy from the sun evaporates water from land and sea, turning it into water vapour. water also evaporates from plants through transpiration
  • warm water vapour carried upwards as warm air rises, until it cools and condenses into clouds
  • water falls from clouds as precipitation onto land as fresh water
  • water drains into the sea
• organisms turn atmospheric elements into complex compounds that are passed up the food chain or turned into waste products in decay
• materials decay because they are broken down and digested by microorganisms (happens faster in warm, moist and aerobic conditions, because microorganisms are more active)
• decay puts stuff back into the soil
• stable community: materials taken out are balanced by materials put back in
• carbon cycle:

  • co2 removed from atmosphere by green plants and algae in phs. carbon used to make glucose, used to make carbs, fats and proteins to make up bodies of plants and algae
  • plants and algae respire, returning carbon as co2
  • plants and algae eaten, carbon becomes fats and proteins in them. carbon moves up food chain.
  • animals respire, " "
  • plants, algae and animals die, detritus feeders and microorganisms digest them. they respire, " "
  • combustion of wood and fossil fuels " "
• compost - decomposed organic matter, used as a natural fertiliser.
• rate of decay:

  • temp: warm (increase rate enzymes work at). too hot, rate decreases because enzymes denature, etc.
  • o2: high (organisms need to respire and survive)
  • h2o: high (needed for biological processes)
  • number of decay organisms: more
• biogas:

  • methane, burned as fuel
  • microorganisms decay stuff anaerobically, which produces methane, or sludge waste from sewage works can be used
  • biogas is made in a fermenter (digester or generator) they need to be kept at a constant temperature for the microorganisms to respire
  • biogas can't be stored as a liquid (needs high pressure) so it has to be used straight away for heating, cooking, lighting or to power turbines to generate electricity
• batch generators:

  • small
  • manually loaded with waste
  • by-products cleared at end of each session
• continuous generators:

  • produce constantly at steady rate
  • waste continuously fed in
  • large
• generator:

  • inlet for waste
  • outlet for waste digested material to be removed (fertiliser)
  • outlet for biogas to be piped where needed