6186970
Description
Flashcards by Mel Hughes, updated more than 1 year ago
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Created by Mel Hughes
over 7 years ago
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| Question | Answer |
| Name a hard part of an animal which will not decay easily | One of: Bones, teeth, shells, claws |
| Why are some fossils destroyed over time? | Due to geological activity which breaks them up or wears them away |
| How can a new predator cause extinction of a species? | It eats all the animals |
| Suggest another factor could have caused the dinosaurs to die out | A new disease being introduced into the population. It is unlikely to be a new predator because dinosaurs were at the top of the food chain |
| How do populations become isolated? | Islands break away from the mainland, new rivers form, mountain ranges or craters separate them |
| What is meant by genetic variation? | The wide range of alleles that control the characteristics in a population |
| How old is the Earth? | About 4.5 billion years |
| When do we think life on Earth began? | About 3.5 billion years ago |
| How are fossils dated? | It is possible to date the rocks so the fossils are the same age as the rocks they are preserved in |
| Why are there no fossils of early life forms? | Early life forms were soft bodied and did not form fossils |
| What is the shortest way to represent three billion in numbers? | |
| How might a new competitor cause the extinction of some species? | The original species may be left with too little to eat |
| Suggest two ways that people can cause the extinction of some species | Two of: By hunting them for food, by removing the habit of the species, through polluting the environment, by introducing new competitors to the species, by accidentally introducing a new disease |
| What are the two main ideas put forward for the extinction of dinosaurs? | A giant asteroid colliding with Earth; Due to sea ice melting and cooling the sea temperature by about 9'C |
| 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 new river, either side of a mountain range |
| What are the stages in speciation? | Reference to isolation of two groups; there is genetic variation in the two populations; alleles are selected which give an advantage; interbreeding no longer possible (as populations diverge/become different); therefore new species are formed (speciation) |
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