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B3 Life on Earth

B3 Life on Earth. Lesson 8: Evolution has the Answer. Objectives. MUST describe how the effects of mutations, natural selection, isolation and environmental change can cause new species to evolve

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B3 Life on Earth

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  1. B3 Life on Earth Lesson 8: Evolution has the Answer

  2. Objectives • MUSTdescribe how the effects of mutations, natural selection, isolation and environmental change can cause new species to evolve • SHOULD explain how scientists can make predictions about what might fill ‘gaps’ in the fossil record

  3. Key Words • You need to be able to define the following: • Mutation • Evolutionary change • Fossil record • Isolated (habitat)

  4. Textbook Answers 1) In the fossil record. 2) Because these might make them more likely to have more offspring. 3) If species are isolated from each other, natural selection will act separately on each of the populations; because the habitats are likely to be different, different genes are likely to become more frequent in each of the populations; over time the species will become so different that they are unable to reproduce with each other and so will have formed new species.

  5. Textbook Answers 4) They may not be able to respond to changes in their environments quickly enough and so may die out; evolutionary change due to natural selection takes place over thousands or millions of years, and the climate is currently changing more quickly than that; bluebells are under threat from climate change because they have previously had an advantage due to their ability to flower earlier than other plants; Warmer spring seasons mean that other plants they previously did not have to compete with will out-compete them for light and space. 5) We now have the technology (such as DNA analysis) to confirm how species are related to each other and can construct accurate ‘trees’ that show the evolutionary relationship of organisms; we also have many thousands more fossils in the fossil record that match the predictions of what would be found. 6) For example, by looking at how a species started out and how it ended up, and imagining what it might have looked like part way through the change.

  6. Worksheet Answers Activity 1 (Low demand) • a) genes; b) offspring; c) more often than other genes; d) very long periods of time; e) fertile offspring; f) species Activity 2 (Standard demand) • A−4; B−1; C−2; D−3 Activity 3 (High demand) 1) About 3500 million years ago. 2) There is such a vast range of habitats available on Earth. 3) Scientists have been able to pinpoint using DNA the points at which organisms shared a common ancestor. 4) It is shaped like a tree, with branching paths; at each node of the path, organisms on the following branches share a common ancestor.

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