Chapter 18

    Cards (18)

    • Biodiversity = the variety of different species in an ecosystem.
    • high biodiversity = ensures the stability of an ecosystem and the survival of species
    • levels of carbon dioxide and methane in the atmopshere are increasing due to human activity which contributes to global warming and climate change
    • global warming = gradual increase in the average temperature of the earth
    • global warming has resulted in:
      • extreme weather and sea level changes
      • large scale habitat change
      • threats to security and availability of food
      • migration of species to different parts of the world
    • Food security = having enough food to feed a population
    • Factors threatening food security:
      • rapid population growth
      • environmental changes
      • conflict
      • new pests and pathogens
      • changing diets
      • increasing costs of agricultural inputs
    • intensive farming techniques - make food production more efficient by restricting energy transfer from food animals to their environment
    • intensive farming methods:
      • limiting movement of the animals
      • controlling the temperature of their surroundings
    • How to maximise yield:
      • feed animals high protein foods
      • give animals antibiotics to prevent disease
      • regularly use fertilisers , herbicides and pesticides on crops
    • Sustainable fisheries - use net sizes and fishing quotas to ensure that fish stocks are not overfished
    • Advantages of Intensive Farming:
      • high yield + quicker growth of crops and animals
      • efficient use of food with less waste produced
      • can meet demand for food
    • Disadvantages of Instensive Farming:
      • increased risk of antibiotic resistant bacteria strains
      • large carbon dioxide and methane emissions
      • Ethical issues
      • pesticides and herbicides may kill beneficial organisms
    • Deforestation = the removal of trees from an area, usually for agriculture or to make space for housing
    • Large scale deforestation - has been used to provide land for cattle and rice fields and to grow crops for biofuels
    • Result of large scale deforestation:
      • large amounts of carbon dioxide being released into the atmosphere
      • extinctions and reductions in biodiversity
      • climate changes
    • Eutrophication: excessive richness of nutrients in a lake or other body of water, frequently due to run-off from the land, which causes a dense growth of plant life.
    • Process of Eutrophication:
      1. farmer puts fertiliser on crops
      2. rain causes run-off
      3. increased nitrates and phospates in the water (from fertiliser)
      4. overgrowth of algae 'algal bloom'
      5. no light = no photosynthesis , lots of decay = oxygen is used up
      6. plants and fish die