4.1.3 classification

• how does phylogenetic classification organise species

  Phylogenetic classification arranges species into groups according to their evolutionary origins and relationships

  It tells us how closely related species are and how recent their shared common ancestors are
• taxonomic classification system hierarchy

  Domain

  Kingdom

  Phylum

  Class

  Order

  Family

  Genus

  Species
• binomial system


  Made up of genus and species

  The genus is capitalised and the species is lowercase
• what are the 5 kingdoms

  • prokaryote
  • protoctista 
  • fungi 
  • plantae 
  • animalia
• prokaryote

  • unicellular
  • No membrane-bound organelles
  • No feeding system instead absorbs nutrients across the surface or photosynthesises
• protoctista

  • unicellular
  • Does have nucleus and membrane-bound organelles
  • Chloroplasts and cilia
  • Nutrients absorbed by photosynthesis, injection or parasites
• fungi

  • unicellular/multicelluar
  • Membrane-bound organelles
  • No chloroplasts
  • Nutrients absorbed from decaying matter
  • Food stored as glycogen
• plantae

  • multicellular 
  • membrane-bound organelles 
  • chloroplasts 
  • nutrients absorbed by photosynthesis and stored as starch
• animalia

  • multicellular
  • Membrane-bound organelles
  • No chloroplasts
  • Nutrients obtained by ingestion and stored as glycogen
• what did classification use to be based on

  observational characteristics
• what is a classification based on in modern-day

  DNA base sequences and amino acids

  • DNA base sequences of organisms for common genes can now be compared as a measure of how closely related organisms are
  • The more closely related the species the higher the degree of similarity on the base sequences
  • This is because mutations accumulate over time and those species must have evolved from a common ancestor and therefore have had more time to accumulate different mutations resulting in differences
  • Sequence of amino acids
• what are the 3 domains

  • archaea 
  • bacteria 
  • eukaryota
• natural selection

  • The process that leads to evolution
  • Evolution is the change in allele frequency over many generations in a population
  • Natural selection results in species becoming better adapted to their environment
  • Adaptations may be anatomical, physiological or behavioural
• evidence of natural selection

  • fossils (evidence of how species have changed over time)
  • DNA (how closely species are related)
  • molecular evidence
• what are the 3 types of adaptations

  • physiological 
  • anatomical 
  • behavioural
• anatomical adaptations


  internal or physical features
• physiological adaptations


  processes that take place within an organism
• behavioural adaptations


  changes in the way organisms act
• intraspecific variation


  differences between the same species caused by mutations
• interspecific variations


  differences between different species
• continuous variation


  traits controlled by many genes and the environment (height)
• discontinuous variation


  traits controlled by a single gene and environment
• how evolution occurs

  1. New alleles for a gene created by random mutation

  2. If alleles increase their chances of survival in that environment then they are more likely to survive and reproduce

  3. This reproduction passes on advantageous alleles to next-gen

  4. As a result over many generations the new allele increases in frequency in the new population