3 Classification

• Classification


  The process of naming and organising organisms into groups based on their characteristics
• Classification hierarchy from largest to smallest

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• Binomial name


  Generic name= the genus the organism belongs to

  Specific name= the species the organism belongs to
• Advantage of binomial naming system

  • It is universal; an organism's binomial name is the same everywhere in the world
• Five kingdoms


  • Prokaryote
  • Protoctista
  • Fungi
  • Plantae
  • Animalia
• Three domains


  • Bacteria
  • Archaea
  • Eukaryota
• How organisms are classified into a kingdom

  Based on similarities in observable characteristics
• How the domain system of classification was developed

  By analysing molecular differences between organisms to determine their evolutionary relationships (phylogeny)
• Difference between classification and phylogeny

  Classification is simply sorting organisms into groups. Phylogeny investigates the evolutionary relationships between organisms.
• How natural selection results in evolution

  1. Random mutations result in new alleles

  2. Some alleles provide an advantage against selection pressures, making an individual more likely to survive and reproduce

  3. Their offspring receive the new allele, and are said to have 'evolved' a new characteristic
• Darwin and Wallace observed that birds have many different beak shapes, and concluded that birds with beak shapes most suited to the food they eat are more likely to survive and therefore pass this beak shape onto their offspring
• Evidence for the theory of evolution

  • Fossils
  • Genomic DNA
  • Molecular
• Causes of variation


  • Genetic (mutations, random fertilisation, etc.)
  • Environmental (climate, diet, culture, etc.)
• Intraspecific variation


  Variation within the same species
• Interspecific variation


  Variation between different species
• Continuous variation


  Variation exists as gradual changes over a range e.g. height, root length
• Discontinuous variation


  Variation exists as distinct categories e.g. blood group, bacteria shape
• Spearman's rank correlation coefficient

  To measure correlation between two variables, i.e. the extent to which changing one variable affects the other variable
• Interpretation of Spearman's rank results

  Closer to 1= more positive correlation

  Closer to -1= more negative correlation

  Around 0= no correlation
• Three types of adaptation

  • Anatomical (changes to body structure) e.g. oily fur
  • Physiological (changes to bodily processes) e.g. venom production
  • Behavioural (changes to actions) e.g. hibernation
• Organisms from different taxonomic groups may show similar features if they have adapted to similar environments, e.g. marsupial moles and placental moles
• Implications of evolution for humans include bacterial antibiotic resistance and pesticide resistance