Flashcards · Biology · Evidence for Evolution and Classification
Extinction
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When does a species become extinct?
When there are no remaining individuals of the species still alive.
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Name three factors that may contribute to extinction.
New predators, new diseases and new competitors.
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How can environmental change cause extinction?
The species cannot adapt, move or evolve fast enough.
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Give two catastrophic events that can cause extinction.
A massive volcanic eruption and an asteroid collision.
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When did the dinosaurs go extinct?
About 66 million years ago.
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What happened to the climate after the asteroid impact?
It became colder as dust blocked the sunlight.
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Name an animal that humans hunted to extinction.
The dodo.
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How does habitat destruction cause extinction?
The species loses the place and the resources it needs.
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Why are small populations at greater risk?
One event could kill all the individuals, and there is little variation.
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Why does low variation increase the risk?
No individual may have the allele that helps it survive a change.
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What is a mass extinction?
An event in which a large proportion of species die out together.
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Why are island species often at risk?
They have not evolved defences against newly arrived predators.
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How do fossils show that extinction has happened?
Fossils of species that no longer exist are found in rocks.
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Name one human activity that causes global warming.
Burning fossil fuels.
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Is extinction always caused by humans?
No. It has happened naturally throughout the history of life.