B2 Summary

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  • Energy Flow and Recycling
    • Pyramids of biomass and numbers can show feeding relationships
      • Pyramids of biomass are harder to construct but always form pyramids.
        • Energy is lost from each stage of a food chain
          • Food chains are limited to a small number of trophic levels
    • The recycling of Nitrogen involves the action of four types of bacteria
      • Nitrifying Bacteria - Ammonia to Nitrates
      • Denitrifying Bacteria - Nitrates to Nitrogen gas
      • Nitrogen-fixing Bacteria - live in root nodules. Fix nitrogen gas
      • Decomposers (Soil Bacteria and Fungi) - convert proteins and urea to ammonia
    • The recycling of Carbon involves Photosynthesis, Feeding, Respiration and Decompostition
  • B2-Understanding Our Environment
    • Classification and Living Together
      • Organisms can eat each other (predators)
        • Organisms can gain from each other (mutualism)
          • Organisms can feed off of each other (parasites)
      • Organisms are classified into discrete groups starting with Kindom and ending with species.
        • It is difficult to classify intermediate organisms, hybrids and asexual organisms
      • Organisms are classified using natural systems
        • This gives information about evolutionary relationships
      • Similar organisms will compete with each other for food
        • Organisms that share the same niche or are in the same species will compete more
    • Energy Flow and Recycling
      • Pyramids of biomass and numbers can show feeding relationships
        • Pyramids of biomass are harder to construct but always form pyramids.
          • Energy is lost from each stage of a food chain
            • Food chains are limited to a small number of trophic levels
      • The recycling of Nitrogen involves the action of four types of bacteria
        • Nitrifying Bacteria - Ammonia to Nitrates
        • Denitrifying Bacteria - Nitrates to Nitrogen gas
        • Nitrogen-fixing Bacteria - live in root nodules. Fix nitrogen gas
        • Decomposers (Soil Bacteria and Fungi) - convert proteins and urea to ammonia
      • The recycling of Carbon involves Photosynthesis, Feeding, Respiration and Decompostition
    • Adaptation and Natural Selection
      • Organisms in hot, dry areas have adaptations to: increase heat loss, move on sand and  cope with a lack of water.
        • Organisms in cold conditions are adapted to: keep warm and move on the snow
          • Heat loss of an organism depends on its surface area to volume ratio
      • Darwin's theory of natural selection involves variation, competition, survival of the fittest and selective reproduction
        • Darwin's theory was widely criticised at first, but is now widely accepted
          • Examples of  natural selection are: warfarin resistance in rats, antibiotic resistance in bacteria and colours of peppered moths
    • Population, Pollution and Sustainability
      • Pollution can be measured using direct methods or by using indicator species
      • The human population has been increasing exponentially
        • This has led to an increase of pollutants
          • E.g. Carbon Dioxide - Global Warming, Sulphur Dioxide - Acid Rain, CFCs - Breaking down ozone layer
      • Removing waste, producing food and supplying energy sustainably will help conserve habitats and organisms
        • Conservation is important to:
          • Protect our food supply
          • Prevent damage to food chains
          • Protect organisms for medical uses
          • Protect habitats for tourism

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