ADD BIO: Fossils

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What is a fossil?
The remainder of an organism from a long time ago.
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Where are fossils usually found?
In rocks.
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How does formation of fossils happen (mineral replacement)?
1) Teeth, bones etc. don't decay easily, can last a long time when buried. 2) Eventually replaced by minerals as they decay, forming rock like substance shaped like original part. 3) Surrounding sediments turn to rock, fossil stays distinct in rock.
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How does formation of fossils happen (casts and impressions)?
1)When fossils are buried in soft material like clay. Clay later hardens around it, and organism decays leaving a cast of itself. Animal burrow's/plant roots can be preserved as casts.2)Footprints can be pressed into clay when soft,leaving impression
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Why does preservation happen in tar pits and amber?
There is no oxygen or moisture so decay microbes can't survive.
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Why does preservation happen in glaciers?
It's too cold for the decay microbes to work.
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Why does preservation happen in peat bogs?
They are too acidic for decay microbes to work.
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What is amber?
A clear yellow 'stone' made from fossilised resin.
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Why can it be hard to find fossils of early life forms? (2 reasons).
1) Fossils destroyed by geological activities (e.g. movement of tectonic plates). 2) They were soft bodied organisms so they decayed quickly away completely.
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Give two hypotheses of how life began.
1) Simple organic molecules were brought to earth by comets. 2) Life began in a primordial swamp. Simple organic molecules joined to make more complex ones which joined to give life forms.
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Why is it hard to tell if two fossils are from the same species just by looking at them?
If two organisms can reproduce to produce fertile offspring then they are of the same species. It is not possible to tell id two fossilised animals would have been able to do this.
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Card 2

Front

Where are fossils usually found?

Back

In rocks.

Card 3

Front

How does formation of fossils happen (mineral replacement)?

Back

Preview of the front of card 3

Card 4

Front

How does formation of fossils happen (casts and impressions)?

Back

Preview of the front of card 4

Card 5

Front

Why does preservation happen in tar pits and amber?

Back

Preview of the front of card 5
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