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External links

• NCEA on TKI
• NZQA website

Biology 2.3 Describe genetic variation and change

Subject content

Make sure you have up-to-date course notes. Use them, and if you haven't got them, see your teacher.

These are the biological concepts and processes you may be tested on:

• Genetic variation:
  
  • genetic biodiversity – allele frequencies, gene pools
    (check out the New Zealand Evolutionary Evidence for both modern and fossil examples)
  • mutation as a source of variation (but details of types of mutation are not required)
  • independent assortment, segregation, and recombination during meiosis
  • dihybrid inheritance – this involves completing Punnett squares of a simple dihybrid cross of recessive/dominance. Prediction of proportions of likely genotypes and their associated phenotypes is expected.
  
  
• Genetic change, ie where the gene pool is affected:
  
  • natural selection
  • migration
  • mutation
  • genetic drift and the founder effect
  • bottleneck effect.

There are lots of suitable tutorials at the following websites that relate to the topics of NCEA level 2. Check out the biological concepts and processes here:

• S-Cool: Biology – Genetics. The gene interactions section is a level 3 topic.

You need to understand:

• that genetic change involves processes acting on genetic variation within populations over time
• that variation is inherited, that it is provided by sexual reproduction and mutation, and that it is acted upon by selection pressures to provide change to a population over time
• mechanisms of meiosis and fertilisation at a cellular and sub-cellular level, and the concepts of change to populations over time.
  
  

Check the links page for this standard also as there are many useful ones to help revision.

Don’t forget to revise last year’s work at NCEA level 1. Try BBC Bitesize Revision: Inheritance.

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