It is possible to date the rocks, so fossils can be dated by the rocks they are discovered in.
3 of 16
Why are there no fossils of early life forms?
Early life forms were soft bodied and did not form fossils.
4 of 16
What is the shortest way to represent 3 billion in numbers?
3 X 10 (power 9)
5 of 16
How might a new competitor cause the extinction of a species?
The original species may be left with too little to eat.
6 of 16
Suggest two ways that people can cause the extinction of some species.
By hunting them for food, by removing the habitat of a species, polluting the environment, by introducing new competitors, by accidentally introducing a new disease.
7 of 16
What are the two main ideas put forward for the extinction of the dinosaurs?
A giant asteroid colliding with earth. By the sea ice melting and cooling the sea temperature by 9 degrees celsius.
8 of 16
What is meant by geographical isolation?
Two populations of an organism become separated and live in two different regions. e.g two sides of a river or mountain range.
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What are the stages in SPECIATION?
Isolation, genetic variation in two population, alleles are selected that give an advantage, interbreeding no longer possible, therefore new species formed (SPECIATION)
10 of 16
Name a hard part of an animal that will not decay easily.
Bones, teeth, shells, claws.
11 of 16
Why are some fossils destroyed over time?
Due to geological activity which breaks them up or wears them away.
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How can a predator cause the extinction of a species?
It eats all the animals.
13 of 16
What is meant by genetic variation?
The wide range of alleles that control the characteristics in a population.H
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How are fossils formed?
From the hard parts of an animal, eg bones, claws etc. From organisms that may have been preserved by ice etc. As preserved traces of animals, footprints etc.
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How can extinction take place?
A new disease, predator, change in environment, new competitor, natural changes in species over time, single catastrophic event.
16 of 16
Other cards in this set
Card 2
Front
When do we think life on earth began?
Back
About 3.5 billion years ago.
Card 3
Front
How are fossils dated?
Back
Card 4
Front
Why are there no fossils of early life forms?
Back
Card 5
Front
What is the shortest way to represent 3 billion in numbers?
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