Ecology

• Interdependence - if one species is removed it can impact the whole community
• What do organisms in an ecosystem compete for?

  • Food
  • Water
  • Space
  • Light
  • Carbon dioxide or oxygen
  • A mate
• Abiotic factors - non-living factors in an ecosytem
• Biotic factors - living factors in an ecosystem
• How do we sample an ecosystem?

  • Place a quadrat in random positions in an area (ideally 10% of that area, using random number generator to choose locations)
  • Count number of chosen organisms in each, then calculate mean by multiplying by total area to get an estimate for population
• Food chains - shows the direction of biomass transfer between organisms
• Apex predators - top of the food chain, have no natural predators above them
• Organisms exist in trophic levels, and their populations fluctuate over time
• Decomposition can be used to produce natural fertilisers to help crops grow. It can also produce methane gas for use as a fuel.
• Peat bogs are being destroyed to make compost
• Water vapour is responsible for 95% of the greenhouse effect
• Biomass is lost between trophic levels through excretion
• Food security is a current big concern
• farmers are trying to farm more efficiently by increasing biomass input while reducing wasted biomass
• Sustainable fishing ensures fish aren't caught faster than they breed, so populations can remain constant.
• GM crops can increase yields.
• There are 5 kingdoms
• Transects measure distribution of a population
• Quadrats measure abundance of a population.
• Explain what sampling means and why it is often used.

  Sampling means only counting a subset of the organisms in a habitat, and it would take ages count all the organisms
• Detritus feeders include worms and woodlice
• Why could the rate of decomposition fall if soil becomes waterlogged?

  Less oxygen, less aerobic respiration, and fewer chemical reactions.
• Explain why maintaining high biodiversity is important.

  It increases the stability of the ecosystem, so that changes are less likely to have adverse affects Many species provide specific services, such as pollination Many of our medicinal drugs come from wild species
• How can the government encourage businesses (including farmers) to reduce damage to biodiversity?


  - Set laws prohibiting or requiring certain things

  - Pay businesses for carrying out certain practices (like planting hedgerows)

  - Setting quotas or limits on harmful practices (such as quotes for deforestation)