6.1 and 6.2 The Origins Of Life on Earth/Exploring the Fossil Evidence Flashcards Preview

GCSE Biology 2.6 Old and New Species > 6.1 and 6.2 The Origins Of Life on Earth/Exploring the Fossil Evidence > Flashcards

Flashcards in 6.1 and 6.2 The Origins Of Life on Earth/Exploring the Fossil Evidence Deck (16)
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When did life approx begin on earth?

3500million years ago


How old is the earth predicted to be?

4500million years old


What is the debate for where life on Earth came from?

Life developed due to the conditions on earth or simple life forms arrived from a different planet


What is meant by dating rocks?

As fossils are found in rocks, we can date when the different organisms existed


Why are scientists not clear about when life on Earth existed?

There is no repeatable or reproducible evidence


Name 4 ways fossils can be formed.

•from the hard parts of animals that can't decay, eg. Bones, teeth, shells and claws
•from organisms that haven't decayed due to the lack of conditions for decay when they died, eg. Preserved in ice
•when the parts of the organism are replace by other materials such as minerals when they decay
•as preserved traces of organisms, eg. Footprints, burrows and rootlet traces


Why did most organisms that does not leave a fossil?

The exact conditions for fossil formations were not present


What are fossils?

The remains of organisms that lived many years ago which are found in rock


Why did most early life forms not leave a fossil?

They had soft bodies so few traces were left behind


Why are traces that were left behinds likely to have been destroyed?

Geological activity such as earthquakes would have destroyed them


Name 3 reasons the fossil record is incomplete

•soft bodied organisms didn't leave fossils
•many organisms died without the exact conditions for fossil formation
•some fossils have been destroyed over time


What can we learn from fossils?

How different organisms have changed as life developed on earth


Why can prehistoric remains stay in good shape in either glaciers, bogs or tree sap?

There is no oxygen reaching them there so they can't decay


Name 3 places where fossils can't decay due to lack of oxygen

•ancient tree sap


Name 7 reasons for extinction in organisms

•new diseases
•new competition
•new predators
•no food
•environment dies
•habitat changes
•single catastrophic events


Give 2 examples of habitat changes that could cause extinction of organisms

•rain forests being cut down