5.2 Natural selection

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5.2 Natural selection

5.2 Natural selection



Essential idea:


5.2.1  The diversity of life has evolved and continues to evolve by natural selection.


Natural Selection Video 



Nature of science:


5.2.2  Use theories to explain natural phenomena—the theory of evolution by natural selection can explain the development of antibiotic resistance in bacteria. (2.1)




5.2.3  Natural selection can only occur if there is variation among members of the same species.


5.2.4   Mutation, meiosis and sexual reproduction cause variation between individuals in a species.


5.2.5   Adaptations are characteristics that make an individual suited to its environment and way of life.


5.2.6   Species tend to produce more offspring than the environment can support.


5.2.7   Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.


Antibiotic resistant bacteria


5.2.8   Individuals that reproduce pass on characteristics to their offspring.


5.2.9   Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.


Tutorial natural selection




5.2.10     Application: Changes in beaks of finches on Daphne Major.


5.2.11     Application: Evolution of antibiotic resistance in bacteria.


Evolution lab interactive animation





5.2.12  Students should be clear that characteristics acquired during the lifetime of

an individual are not heritable. The term Lamarckism is not required.


Theory of knowledge:


5.2.13  Natural Selection is a theory. How much evidence is required to support a

theory and what sort of counter evidence is required to refute it?


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