1. From the hard parts of animals that do not decay easily 2. Parts of animals which have not decayed due to the lack of conditions needed for decay 3. Parts of organisms are decayed 4. Preserved traces of organisms
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What are the 3 explanations as to why fossils are not present?
1.The exact conditions for fossil formation were not present 2. Many life forms had soft bodies 3. Traces could have been destroyed by geological activity
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Define extinction
Species that once existed have now completely died out
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Name the 6 factors that effect extinction
1. Disease 2. Environment change 3. Predators 4. competition in an area 5. Single catastrophic event 6. Natural changes over time
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What are the 2 ideas scientists have come up with to explain the extinction of dinosaurs?
1. Collision with a giant asteroids caused a chain of catastrophic events 2. Less food available due to altering climate
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How can species arise from existing species?
Isolation
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What is geographical isolation?
A division between 2 areas
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State the stages in which new species arise?
1. Separation due to geographical isolation 2. Genetic Variation - wide range of alleles that control their characteristics 3. Natural selection will occur 4. Different environment means they will evolve differently 5. Speciation
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What does Speciation mean?
When two populations can no longer interbreed.
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What does genetic variation mean?
A population has a wide range of alleles that contolr their characteristics
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Name a hard part of an animal which will not decay easily?
Bones, teeth, shells and claws
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Other cards in this set
Card 2
Front
What are the 4 ways fossils can be formed?
Back
1. From the hard parts of animals that do not decay easily 2. Parts of animals which have not decayed due to the lack of conditions needed for decay 3. Parts of organisms are decayed 4. Preserved traces of organisms
Card 3
Front
What are the 3 explanations as to why fossils are not present?
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