B3 Life on Earth Summary

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  • Created by: Farhana
  • Created on: 15-12-12 17:25
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  • Species- group of organisms that can breed= FERTILE offspring
    • Species adapt to their environment
      • Fish- gills=extract O2 from H2O, tail fins=large surface area, streamlined, swim bladder
      • Cactus- thick stem= store H2O, rounded shape= small surface area reducing H2O loss, shallow extensive roots=water
      • Every living thing needs resources from its environment - 1.Light(pl), 2.Food(an)(minerals=plants), 3.Oxygen(pl+an), (CO2-pl), 4. Water(all)
        • Any change in the environment has all effects on the food cycle e.g. less food = competiton = extinction
          • 3 changes that can cause extinction:
            • 1. Environmental conditions change- can't adapt
            • 2. New species intro-ed, competitor, disease organism, predator of them
            • 3. An organism in its food web becomes extinct
          • Energy is lost from organism to organism in the food cycle
            • Energy form the sun is the source of energy for nearly ALL life
              • Plants use 10% of the sun's energy during photosynthesis and the 90%'s lost
            • The energy is lost in respiration, heat (to surroundings), waste, movement
            • Remaining energy is transferred to predator when eaten or eaten waste
              • Efficiency of energy transfer- efficiency= energy available to next stage ÷ energy that was available to previous stage
                • The energy is lost in respiration, heat (to surroundings), waste, movement
          • Environmental change can be measured by temperature measurements, nitrate level-water, CO2 level-air
            • Lichen-air pollution, sensitive to sulphur dioxide. Mayfly Nymphs- sensitive to level of oxygen>water's clean if there. Phytoplankton- increase when levels of nitrates+ phosphates in H2O increase
    • Individuals of the same species have differences- variation
      • This is due to mutations e.g. from radiation/chemicals, mistakes when genes copied
    • Species can change to adapt to their environment through Natural Selection
      • Natural selection causes evolution and means "survival of the fittest"
        • Selective breeding is when humans choose a feature they want to appear in the next generation e.g. most milk
        • Survival characteristics get passed down because more likely to survive through competition of limited resources
        • Evolution can produce new species
          • Species can become isolated so can't interbreed
            • Factors to make diff. species: Diff. mutation create diff feature in the organisms, Natural selection, Environmental changes = diff. adaptations
          • Life began around 3500 million years ago
            • Fossil records + DNA provide evidence for evolution
              • Fossil records show species getting more complex over time, Mutations in DNA still similar/related to living species
        • Charles Darwin- theory of evolution by natural selction, by observations
          • Lamarck- theory if characteristic used more= more developed = passed to offspring
    • The rate of extinction of species increasing
      • Mainting biodiversity-important. more plants= more resources for new food crops, chems. in living things= new medicines
        • Biodiversity- no. of diff. species, range of diff. types of organisms, genetic variation between organisms of same species
        • Mainting biodiversity is an important part of sustainability, means future can have what we have now
          • Sustainability means meeting the need's of today's population without harming the environment so that future generations can still meet their own needs
      • Correlation between growth of population+ no. of species extinction
        • Humans can cause extinction directly(e.g. hunting)/indirectly(destroy habitat/intro new species)
    • Millions of species grouped into 5 kingdoms- bacteria, fungi, algae, plants, animals
  • Lamarck's rejected for Darwin's, acquired characteristics don't have a genetic basis = can't pass on
    • Lamarck- theory if characteristic used more= more developed = passed to offspring
    • Charles Darwin- theory of evolution by natural selction, by observations

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