4.2.2

• taxonomic hierarchy

  domain, kingdom, phylum, class, order, family, genus, species
• classification


  the act of arranging organisms into groups based on their similarities and differences
• classification makes it easier to

  identify and study organisms
• going down the taxonomical hierarchy there are

  more groups but few organisms in each group
• kingdoms

  prokaryotae, protoctista, fungi, plantae, Animalia
• prokaryotae


  unicellular, no nucleus or membrane bound organelles, loop of DNA, smaller ribosomes, smaller cells, free living or parasitic, autotrophic or heterotrophic
• protoctista


  single celled, eukaryotic cells, free living, autotrophic or heterotrophic, many forms similar to animals or plants
• fungi


  eukaryotic, multicellular or single celled, chitin cell wall, saprotrophic, cytoplasm is multinucleate, can be mycelium
• plantae


  eukaryotic, multicellular, cellulose cell wall, can photosynthesise, contains chlorophyll, autotrophic
• Animalia


  eukaryotic, multicellular, no cell wall, heterotrophic, motile
• autotrophic


  produce their own food
• heterotrophic


  consume plants and animals
• saprotrophic


  consume decaying matter
• multinucleated


  has more than 1 nucleus in the cytoplasm
• mycelium


  a network of fungi
• motile


  able to move
• domains


  eukarya, archaea, bacteria
• eukarya


  contains protoctista, fungi, plantae and Animalia. anything that has a nucleus
• archea


  have similar histones to eukarya so are genetically closer
• bacteria


  have no histones
• proposal of the 3 domain system

  1990 by carl woese

  molecular evidence - difference in RNA polymerase and histones

  cell membrane evidence - difference in bonds in lipids in cell membrane and a difference in the development and composition of the flagella
• histones


  proteins on DNA
• an organisms name is written


  Genus species in italics or underlined
• artificial classification


  based on a few characteristics and does not reflect evolutionary relationships. done for convenience
• natural classification


  based on many detailed characteristics, reflects evolutionary relationships and is based on homology
• homology


  the existence of shared features that are inherited from a common ancestor
• phylogeny


  the study of evolutionary relationships between organisms shown by phylogenetic trees
• biological species concept


  the ability for two individuals to successfully produce viable, fertile offspring
• phylogenetic species concept


  an irreducible group whose members are descended from a common ancestor and who all possess a combination of certain defining traits
• morphological species concept


  if individuals look similar
• ecological species concept


  if the individuals use the same set of biological resources
• phylogenetic tree

  A) A B C D E

  B) A B

  C) Root

  D) ancestors

  E) present day

  
• monophyletic


  share 1 common ancestor
• Darwin's contributions to evolution

  Proposed natural selection and observed:

  • offspring appear similar to their parents
  • organisms have the ability to reproduce in large numbers
  • populations usually always remain stable in size
  • no two individuals are identical
• Wallace's contributions to evolution:

  also proposed natural selection

  • most individuals are found in a habitat where they are best fitted for their environment
  • geographical boundaries mark species boundaries
  • some organisms have advantageous adaptations evolved by natural selection
• evidence of evolution


  fossil evidence

  comparative anatomy

  comparative biochemistry
• fossils


  a mineralised or preserved remains of an organism or traces of their activity. May also be found in amber or peat bogs

  dies + decomposes -> buried under sediment -> high temperature + pressure -> bones dissolve -> minerals crystallise in the space
• how do fossils show evolution

  fossils of simple organisms are found in much older rock compare to complex organisms hat are found in newer rock. The sequence of the organisms match their current ecological links

  similarities in anatomy of fossils and living organisms
• why do fossils not support evolution well

  the fossil record is incomplete as it is difficult for fossils to form
• how comparative anatomy shows evolution

  organisms have homologous structures suggesting they have evolved from a common ancestor