B2F

B2F

1. Evolution takes place over millions of years

2. Organisms most suited to their environment are more likely to survive

3. 'Survival of the fittest'

4. Organisms which cannot adapt to their surroundings may become extinct

5. Natural selection depends on genetic variation

6. Knowledge of inheritance and DNA supports Darwin's theory of natural selection

7. Lamarcks theory of evolution states that characteristics acquired during an organisms lifetime are passed on to the next generation

8. Life on Earth today exists because of the conditions that were present when life was evolving. If, in the past, conditions had been different eg hotter, colder, or the Earth more or less massive, then evolution by natural selection could have produced some very different results. Our bodies would have changed to suit the Earth's conditions.

9. The basic idea behind Darwins theory of evolution is that all the different species have evolved from simple life forms. These simple life forms first developed more than 3 billion years ago (the Earth is about 4.5 billion years old). The timeline below shows some of the key events in the evolution of life on Earth, from the first bacteria to the first modern humans.

10. New species can arise as a result of isolation. This is where two populations of a species become geographically separated.

11. Genetic variation - where each population has a wide range of alleles that control their characteristics

12. Natural selection - where the alleles which help an organism to survive are selected in each population

13. Speciation - where the populations become so different that successful interbreeding cannot happen anymore

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