Paper 2

• Biodiversity

  The variety of the different species on earth or within an ecosystem
• Importance of biodiversity

  • To maintain the stability of an ecosystem
• How biodiversity ensures the stability of an ecosystem

  It reduces the dependence on particular species for resources eg. food and shelter, so that even if one species is removed other species can still survive
• Rapid rise in human population

  Increase in standard of living
• Where pollution occurs

  • Air
  • Land
  • Water
• Water pollutants

  • Sewage
  • Fertiliser
  • Chemicals
• How eutrophication occurs

  1. Fertiliser from farms pollute the water, causing excessive algae growth, depleting the oxygen in the water, causing other plants and animals to die

  2. Dead plants are decomposed by bacteria and the oxygen level decreases further
• Air pollutants

  • Smoke
  • Acidic gases
• Land pollutants

  • Landfill waste
  • Chemicals
• Human activities that reduce the land available for animals and plants

  • Building
  • Farming
  • Quarrying
  • Disposing of waste
• Why peat bogs have been destroyed

  To produce compost to increase food production
• Destruction of peat bogs

  Releases a large volume of carbon dioxide into the atmosphere
• Reasons for large-scale deforestation

  • To provide land for cattle or rice fields
  • To grow crops to produce biofuels
• Greenhouse effect

  Greenhouse gases trap energy from the Sun as heat in the atmosphere, keeping the temperature on earth suitable for life
• Increase in levels of greenhouse gases

  Causing the temperature on earth to increase
• Harmful effects of deforestation

  • Destruction of many animals' habitats
  • Releases large amounts of greenhouse gases
• Consequences of global warming

  • Rising sea levels
  • Melting polar ice caps
  • Changing weather patterns
  • Migration of animals to find suitable habitats
  • Tropical diseases becoming more common
  • Extinction of species
• Steps taken to maintain biodiversity

  • Breeding programmes for endangered species
  • Protection and rebuilding habitats
  • Replanting field margins and hedgerows
  • Reduce deforestation
  • Reduce carbon dioxide emissions
  • Recycling rather than disposing in landfills
• Purpose of replanting hedgerows and field margins

  There is higher biodiversity in the margins than the fields that they surround
• Population

  A species that occupy the same habitat
• Habitat

  The place in which an organism lives
• Community

  Populations of different species interacting
• Ecosystem

  The interactions between the biotic and abiotic factors in an area
• Food chains

  Show the feeding relationships of different organisms and the flow of energy between the organisms
• Biomass

  The total mass of living material
• Trophic levels

  The stages in a food chain
• Arrows in a food chain

  Represent the direction of biomass transfer
• Simple food chain

  • producer → primary consumer → secondary consumer → tertiary consumer
• Producer

  An organism that makes its own food
• Primary producers

  • Photosynthetic organisms like green plants and algae that trap energy from the sun
• Primary consumer


  An organism that feeds on producers
• Secondary consumer

  An organism that feeds on primary consumers
• Tertiary consumer

  An organism that feeds on secondary consumers
• Predator

  A consumer that kills and eats other animals
• Prey

  An animal that is killed and eaten by another animal
• Pattern of predators and prey in a stable community

  The numbers of predators and prey rise and fall in cycles
• Producers are the first trophic level because they provide all biomass for the food chain (production of glucose via photosynthesis) and the rest of the food chain involves the transfer of this biomass
• Quadrat

  Piece of apparatus used to measure the abundance and distribution of organisms in an area
• Belt transect

  Piece of apparatus used to study the distribution of organisms across a gradient
• Mean

  The average number of organisms