A Level Biology - Origins of Genetic Variation Presentation

This fully editable PowerPoint presentation covers the entire of Topic 8 from the Edexcel Biology B A Level course.

• How are mutations the source of new variations and how do the processes of random assortment and crossing over during meiosis give rise to new combinations of alleles in gametes?

• How does random fertilisation during sexual reproduction bring about genetic variation?

• Understand the terms ‘genotype and phenotype’,’ homozygote and
  heterozygote’, ‘dominance’, ‘recessive’, ‘codominance’ and ‘multiple alleles’.

• Be able to construct genetic crosses and pedigree diagrams.
  Can you explain sex linkage on the X chromosome, including haemophilia in
  Humans?

• Can you explain the inheritance of two non-interacting unlinked genes?

• Do you understand that autosomal linkage results from the presence of alleles on the same chromosome and that the results of crosses can be explained by the events of meiosis, including black/grey body and long/vestigial wing in Drosophila?

• Can you use the chi squared test to test the significance of the difference between observed and expected results?

• Understand that selection pressures acting on the gene pool change allele frequencies in the population, including:
  ●Stabilising selection maintaining continuity in a population

• ●Disruptive selection leading to changes or speciation.

• Understand that sometimes changes in allele frequencies can be the result of chance and not selection, including genetic drift.

Understand that allele frequencies can be influenced by:
● population bottlenecks
● founder effect.

• Understand how the Hardy-Weinberg equation can be used to monitor changes in the allele frequencies in a population.