Old and New Species - B2 Unit 6
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- Created on: 28-04-14 19:47
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- Old and New Species - B2 Unit 6
- The Origins of Life
- Scientists cannot be exact about when life started on Earth
- There is little repeatable or reproducible evidence
- Fossil are remains of organisms from many years ago which are found in rocks
- We can learn how different organisms changed
- Different ways of formation
- Hard parts that don't decay easily - bone, teeth, shell
- Conditions needed for decay not present - lack of oxygen
- Buried deep underground or in ice
- Parts of animal mineralise - turn into rock
- Preserved traces - footprints, feaces, burrows
- Early life forms mainly sot bodied so left no fossil
- Approx
- Earth began 4500 million years ago
- Life began 3500 million years ago
- Scientists cannot be exact about when life started on Earth
- Exploring the Fossil Evidence
- Fossil record can show how much organisms have changed over time
- some have evolved then become extinct
- Extinction
- A species that once existed has completely died out
- Causes
- A new disease kills
- Environment changes
- New predator may evolve
- A new competitor may evolve using all the resources
- A single catastrophic event
- Volcanic eruption
- Metorite
- Sudden climate change
- Occurs only when there is a change
- Fossil record can show how much organisms have changed over time
- Isolation and Evolution of New Species
- New species can evolve from existing
- Natural cycles linked to environmental change
- New species arise when two populations become isolated
- Organisms of the same species are separated by something they cannot cross
- Geographical isolation
- Organisms adapt to the environment they're in
- Organisms of the same species are separated by something they cannot cross
- Speciation - caused by isolation + geographical change
- Each population has own set of alleles control characteristics needed for environment
- natural selection
- Each environment has different predators, food supply and environment
- evolve differently
- speciation has occurred when the two populations that were once the same species can no longer successfully interbreed
- Each population has own set of alleles control characteristics needed for environment
- New species can evolve from existing
- The Origins of Life
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