classification

• Classification


  The organisation of organisms into groups
• Taxonomy


  The classification of organisms into taxa: kingdom, phylum, class, order, family, genus, species
• Five kingdoms


  • Animals
  • Plants
  • Fungi
  • Protists
  • Prokaryotes
• As you move down the hierarchy of taxa

  The number of organisms in each taxon group decreases
• Advancements in science that led to reconsidering the five kingdoms classification system

  • Microscopes
  • Biochemistry
  • DNA and RNA analysis
• Three domains system of classification


  Organisms are initially divided into three groups: Archaea, Bacteria, Eukarya. Then domain, kingdom, phylum, class, order, family, genus, species.
• Domain Bacteria


  Consists of true bacteria e.g. E.coli
• Domain Archaea


  Consists of primitive microorganisms, contains extremophiles - adapted to live in extreme conditions e.g. hot springs
• what were classifications traditionally based on

  Traditionally, organisms were grouped based on similarities and differences in their anatomy and behaviour
• why was the traditional classification wrong

  Some closely related species may look very different if they live in different habitats e.g. queen ants, worker ants , Organisms that are not closely related may look alike and behave similarly if they live in the same environment e.g. sharks and dolphins
• what are the 3 domains

  three domain , eukarya , archaea , bacteria
• what domain do eukarytoic cells belong to

  eukarya
• what domain do prokaryotic cells belong to

  archaea , bacteria
• domain eukarya

  all eukarya have a nucleus in there cell
• why was the 3 domain system suggested

  as it was discovered using rna sequencing that some species arent as closely related as previously thought despite them living in the same environment
• why may certain species go extinct

  due to selction pressures and competition from other species , e.g food , environment , disease , climate change
• what is Selective breeding

  The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with similar phenotypes
• procedure for Selective breeding

  1. Identify a desired characteristic

  2. Select parent organisms that show the desired traits and breed them together

  3. Select offspring with the desired traits and breed them together

  4. Process repeated until all offspring have the desired traits
• Advantage of selective breeding

  • Creates organisms with desirable features: Crops produce a higher yield of grain, Cows produce a greater supply of milk, Plants produce larger fruit, Domesticated animals
• Other uses of selective breeding

  • In medical research
  • In sports e.g. horse racing
• Disadvantages of selective breeding

  • Reduction in the gene pool (which becomes especially harmful if sudden environmental change occurs)
  • Inbreeding results in genetic disorders
  • Development of other physical problems e.g. respiratory problems in bulldogs
  • Potential to unknowingly select harmful recessive alleles