GCSE biology

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Anonymous
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143170
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GCSE biology
Updated:
2012-03-22 14:20:14
Tags:
evolution biology unit one point booklet part two
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revision
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  1. define the term evolution
    changes in the characteristic of species over time
  2. when do scientists think life on earh began
    3 billion years ago
  3. how many species of living organisms exist today
    30 million
  4. how many species of living organisms are thought to have existed since life on earth began
    3 billion
  5. what has happened to most of the organisms that are though to have existed scince life on earth began
    most of them have become extinct
  6. scientists have collected a lot of evidence for evolution from
    fossils
  7. what are fossils
    they are the remians or partial remians of organisms that lived in the past found preserved in rock or evidence of organisms having been there
  8. what can fossils tell us
    • the shape of an animal
    • the size of an animal
    • what age the animale lived in
    • what the animal looked like in terms of structure and apperance
  9. fill in the blanks to describe how fossils were formed
    when an animal ..... , the .... parts of its .... .... leaving the .... parts such as ..... and .... . .... ... and ...... develop in the ..... . ..... work thier way into it and gradually replace it and fossils are formed
    there are other kinds of fossils such as .... , which become .... by .... and .... into .....
    in other cases a .... is produced when a .... .... becomes .... in .... . the organism .... leaving a ..... (or ....) which shows the .... of an organism
    another method is where animals have become .... by a ..... ... which stops them .... e.g .... , ... and ....

    • dies
    • soft
    • body
    • decay
    • hard
    • bones
    • teeth
    • tiny holes
    • spaces
    • bone
    • minerals
    • ---------------
    • footprints
    • covered
    • mud
    • harden
    • rock
    • -----------
    • mould
    • dead organism
    • buried
    • mud
    • decays
    • space
    • mould
    • shape
    • -------------
    • covered
    • natural preservative
    • decaying
    • amber
    • ice
    • tar
  10. which part of the organism remains after the soft parts have decayed
    bones and teeth
  11. give 2 examples of a soft part of an animal
    • tissue
    • organ
  12. explain how a mould is produced
    a mould is produced when when a dead organism becomes buried in mud . the organism decays leaving a space (or mould) which shows the shape of the organism
  13. give two examples of natural preservatives
    • amber
    • ice
  14. what use is the information which is obtained from fossils
    we can find out what the organisms looked like
  15. fossils allow us to see the .... between .... ...... and ..... .....
    • relationship
    • present organisms
    • past organisms
  16. to our knowledge only a tiny fraction of the organisms which have died have become fossilised . suggest a possible reason for this
    • lots of animals may just have been soft bodied
    • many fossils are very deep in the earths crust and sea bed therefor we may have just not found them yet
  17. suggest 2 possible reasons why animals may become extinct
    • natural disasters
    • food shortages
  18. name a long extinct species
    • dodo
  19. name a more recently extinct species
    golden toad
  20. define species
    a group of organisms that have many chracteristics in common and are able to breed together
  21. fill in the table below with the main features of each of the subgroups of verterbrates
  22. The question is this. In your reading of this tree, which group is the most closely related to fishes: frogs, lizards, birds, cats, or humans?
    frogs

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