ecology

• what is a population?

  all the organisms of a particular species that live in that habitat
• what is a community?

  all the living things in an ecosystem
• what is an ecosystem?

  the interaction of a community between living and non living things
• competition

  • animals compete for mates, territory and food
  • plants compete for light, water, space and minerals
• what is interdependance?

  when all organisms rely on eachother
• what are biotic factors?

  • predators
  • food availability
  • diease
• what are abiotic factors ?

  • light intensity
  • co2 concentration
  • temperature
  • moisture levels
  • pH of soil
• adaptations

  structural → physical structures that help an organism survive

  behavioural → the way an organism acts to survive

  functional → bodily processes that help organisms survive
• what are extremophiles?

  bacteria or archaea found in extreme environments
• predator prey cycles

  • the cycles are out of phase
  • number of predators increase because there are a lot of prey
  • number of predators decrease because there is less prey
• the water cycle

  1. sun causes water to evaporate
  2. the water vapour condenses into clouds
  3. water comes down as precipitation
  4. water seeps into soil, flows into rivers or get taken up by plants
  5. cycle repeats
• the carbon cycle

  1. plants take in carbon by photosynthesis
  2. they either respire or get eaten by animals which respire
  3. when organisms die they decay by microorganisns which release carbon
  4. if they respire anaerobically they form fossil fuels
  5. fossil fuels are burnt
• what is decomposition?

  the process which dead organic matter is broken down into simpler substances
• what are detritus feeders?


  small animals like worm and woodlice that feed on dead organic matter
• what are decomposers?

  microorganisms such as bacteria and fungi
• factors that affect the rate of decomposition

  oxygen → more oxygen leads to more aerobic respiration and if more energy is available there is a faster rate of decomposition

  temperature → particles have more kinetic energy and enzymes can work better

  water → decomposers need water to survive. if soil becomes waterlogged oxygen levels can fall

  compost → mixture of decayed material
• biogas generators

  • some microorganisms carry out anaerobic respiration
  • this produces a mixture of gas called biogas, mostly methane
  • when methane is combusted it releases a lot of energy
  • large containers where plant matter decays anaerobically
  • once it is removed it becomes a sludgy material that has useful materials
• what is biodiversity?

  the variety of different species on earth or within an ecosystem
• ways we reduce biodiversity

  1. obtaining raw materials for resources
  2. producing waste which kills habitats
• pollution can occur in

  water → sewage and toxic chemicals

  land → landfill

  air → smoke and acidic gases
• ways land is reduced

  1. buildings
  2. quarrying
  3. agriculture
• why does deforestation occur?

  1. to raise cattle and for rice fields
  2. for crops
• main issues with deforestation

  1. less co2 will be taken in and less oxygen will be produced
  2. when burned all the co2 that was stored will be released
  3. reduces biodiversity
• peat bogs

  • soil that is acidic and waterlogged
  • microorganisms cant survive
  • made up of partially rotting plants
  • carbon sinks
• peatbogs are

  1. drained for farmland
  2. can be used as fuels
• the atmosphere is a protective layer of the earth that acts as a greenhouse
• The sun

  1. heat energy comes down as light rays
  2. goes through the atmosphere and hits the earth
  3. sunlight could be reflected back into space or absorbed by the particles in the atmosphere
  4. each particle passes on the energy gradually heating the earth
• breeding programmes

  • for endangered species
  • breeding them together
  • release them back into the wild in protected conditions
• protection and regeneration

  when rare and endangered species are put in nature reserves and national parks
• hedgerows

  • provide lots of biodiversity
  • acts as a barrier
• reducing co2 emissions

  • controlling the amount of deforestation
• recycling

  • producing less landfill
  • less toxic chemicals in the air
• trophic levels

  • only 10% of energy get passed on
• apex

  have no predators
• decomposers and detrivores recycle nutrients by returning them back to the ground so producers can use them again
• efficiency of biomass

  biomass that was transferred ÷ biomass that was available x 100
• biomass is lost because

  • organisms dont eat every part
  • they might not be able to break everything down so it leaves as faeces
  • energy is used for respiration
• why do we fish farm?

  • to avoid over fishing
  • reduce the threat to fish species
  • to maintain fish stocks
• increasing the size of fishing nets

  • allows young fish to escape
  • they can grow and reproduce
  • maintains populations
• fishing quotas

  • set limits on the number of fish that get caught
  • maintains balanced ecosystems