Topic 7 - Ecology

• An ecosystem is the interaction between a community of living organisms and their environment.
• • A community is two or more populations of organisms.
• • A population is all the organisms of the same or closely-related species in an area.
• Producers are plants and alga, they make their own food by photosynthesis
• Primary consumers are herbivores which eat plants and other primary consumers
• Secondary consumers are carnivores, which eat primary consumers
• Interdependence means that all the organisms in an ecosystem are dependent upon each other
• Population is all the members of a single species that live within a geographical area
• Species


  A type of organism that is the basic unit of classification. Individuals of different species are not able to interbreed successfully
• Abiotic factors are non-living
• Habitat


  The place where an organism lives
• Population


  All the organisms of one species living in a habitat
• Community

  The populations of different species living in a habitat
• Abiotic factors:

  • moisture levels
  • light intensity
  • temperature
  • carbon dioxide levels (for plants )
  • wind intensity and direction
  • oxygen levels (for aquatic animals )
  • soil ph and mineral content
• Biotic factors:

  • new predators arriving
  • competition - one species may outcompete another so that numbers are to low to breed
  • new pathogens
  • availability of food
• Bacteria can be engineered to produce human insulin:

  • Plasmid removed from bacterium
  • insulin gene cut out human chromosome
  • plasmid cut open
  • plasmid and human insulin gene mixed together
  • ligase is added
  • inserted into bacterium
  • modified bacterium grown in a vat under controlled conditions
• Mycoprotein is used to make high-protein meat substitutes for vegetarian meals
• Sampling:

  1. Place quadrat in random positions
  2. count number of chosen organism
  3. calcutate mean the multiply by total area to get an estimate for population
• Moving a quadrat with a transect allows you to observe changes in population density over a distance
• Food chains show the directions of biomass transfer between organisms
• Apex predators are always at the top of the food chain, no natural predator
• Organisms exist in tropic levels, and their populations will fluctuate over time
• All life is carbon based
• Carbon is recycled when an organism dies and decomposes
• Decomposition can be used to produce natural fertilisers to help crops grow. It can also be used to produce methane gas for use as a fuel.
• Biodiversity 


  the variety of species of organisms that exist in an ecosystem
• High biodiversity makes for a stable ecosystem as organisms will be able to be dependent on a greater number of other species for survival
• Human development results in reduced biodiversity
• ways we reduce biodiversit:

  • land needed for buildings, farming, waiting, disposing waste
  • peat bogs being destroyed for compost - burning peat released co2
  • deforestation
• A pyramid of biomass indicates how much biomass is transferred between tropic levels
• Any % = biomass of 2nd level

  ///////////////////// x 100

  biomass of 1st level
• Biomass is lost at each level
• Food security is current concern due to:

  • changing diets
  • growing environments
  • fuel
  • energy prices
  • cost of farming
  • conflicts
• GM crops increase the yield of crops by 20-30%