evidence for evolution

  • Created by: tia5sos
  • Created on: 22-11-20 19:20
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  • evidence for evolution
    • there is good evidence for evolution
      • scientists believe that all complex organisms on Earth have evolved from simple organisms that existed about 3500 million years ago. Of course, they wouldn't think this without good evidence to back it up.
        • fossil records and antibiotic resistance in bacteria both provide evidence for evolution.
    • Fossils are the remains of plants and animals
      • 1. a fossil is any trace of an animal or plant that lived long ago. They are most commonly found in rocks.
      • 2. They can tell us a lot about what the organisms looked like and how long ago they existed. Generally, the deeper the rock, the older the fossil.
      • 3. By arranging fossils in chronological order, gradual changes in organisms can be observed.
        • This provides evidence for evolution, because it shows how species have changed and developed over many years.
          • For example, if you look at the fossilised bones of a horse, you can put together a family tree to suggest how the modern horse might have evolved.
    • bacteria can evolve and become antibiotic - resistant
      • 1. Like all organisms, bacteria sometimes develop random mutations in their DNA, which introduces new variants into the population. These can lead to changes in the bacterias phenotype
        • for example,, a bacterium could become less affected by a particular antibiotic (a substance designed to kill bacteria or prevent them from reproducing).
      • 2. For the bacterium, this ability to resist antibiotics is a big advantage. The bacterium is better able to survive, even in a host who's being treated with antibiotics, and so it lives for longer and reproduces many more times.
      • 3. This leads to the resistant variant being passed on to offspring and becoming more and more common over time - it's just natural selection.
        • 4. the emergence of antibiotic- resistant bacteria provides evidence for evolution. As bacteria reproduces so quickly, scientists are able to monitor the evolution as it's occuring.


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