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  • Evolution
    • Classification
      • A way of group organisms due to their similar characteristics. Place in groups called kingdoms.
      • Plant Kingdom: Made of many cells. Cells contain chloroplasts. Make their own food by photosynthesis.
      • Animal Kingdom: Made of many cells. No chloroplasts. Unable to make their own food. Most animals move around.
      • Microbe Kingdom: Mostly single celled. Small. Wide group e.g. bacteria and fungi.
    • Speciation
      • A species: organisms of the same type, they can reproduce to produce fertile offspring.
      • Animals of the same species have the same number of chromosomes, different species could produce a hybrid. Often hybrid offspring is infertile due to the amount of chromosomes it has.
      • Speciation: how new species are formed
      • Isolation: members of a species get split apart. Usually this is geographic e.g river, volcanic eruption.
      • Environmental differences e.g. climate, predators: produces different selective pressures. Organisms evolve to be better adapted in their environment.
      • Speciation occurs when the organisms become so different that they can no longer reproduce to produce fertile offspring.
    • Evolution Theories
      • Darwin's theory of natural selection and species evolving from simple life forms which developed was gradually accepted: theory challenged idea of God creating Earth, insufficient evidence at the time, mechanisms of inheritance not known until 50 years later.
      • Lamarck's theory was wrong because genes were passed to offspring at birth
      • Darwin: every species exhibits variation. Traits passed from parents to offspring. Life in wild is competitive, organisms with beneficial traits prosper (improved species evolve).
      • Lamarck: changes happen within a lifetime/characteristics can be acquired in a lifetime. Characteristics then passed to offspring.
      • Mutations cause more rapid changes in species (variation).
      • Evolution trees show a relationship between organisms e.g. invertebrates/vertebrates, fish, amphibians, reptiles, birds, mammals.
      • Other theories: religion, culture, evidence, knowledge, status of theorists/scientists.
    • Evidence of Evolution
      • Evolution: the gradual change of an organism over time.
      • Natural Selection: Survival of the fittest. Large population of variation, fittest survive and pass their genes to their offspring (passing on the advantage).
      • Extinction: A species dies out. Causes: changes in the environment, new predators, new competitors, new diseases.
      • Fossils: mould fossil, resin fossil, body fossil. Trace: comes in the forms of bones.
      • Teeth/bones fossilised, organisms with skeletons are fossilised. Conditions: needs to be buried, lack of oxygen to prevent decay process. During fossilisation: minerals absorbed by bones, matter of bones displaced/becomes rock. Fossils are found by digging or after erosion.
      • The fossil record is incomplete because: fossilisation can't occur in all types of environments (seas/lakes, need anaerobic conditions). Rock cycle/fossil buried underground.
      • Genetic Evidence: looking at the genetic code, you can determine how closely related each organism is.


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