5. evolution

• What can increase variation?

  1. Random mutation
  2. Meiosis and sexual reproduction
• Whats the name of the kind of allele change where both forms of allele variations within a population is balanced?

  Balanced polymorphism
• Cnidaria

  • Have radial symmetry
  • Have a mouth but no anus (single entrance body cavity)
  • May have tentacles with stinging cells for capturing and disabling prey
  • Examples include jellyfish, sea anemones and coral
• Porifera

  • No body symmetry (asymmetrical)
  • No mouth or anus (have pores to facilitate the circulation of material)
  • May have silica or calcium carbonate based spicules for structural support
  • Examples include sea sponges
• Platyhelmintha

  • Have bilateral symmetry
  • Have a mouth but no anus (single entrance body cavity)
  • Have a flattened body shape to increase SA:Vol ratio and may be parasitic
  • Examples include tapeworms and planaria
• Annelida

  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Body composed of ringed segments with specialisation of segments
  • Examples include earthworms and leeches
• Mollusca

  • Have bilaterial symmetry
  • Have a separate mouth and anus
  • Body composed of a visceral mass, a muscular foot and a mantle (may produce shell)
  • Examples include snails, slugs, octopi, squid and bivalves (e.g. clams)
• Arthropoda

  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Have jointed body sections / appendages and have a hard exoskeleton (chitin)
  • Examples include insects, crustaceans, spiders, scorpions and centipedes
• Chordata

  • Have bilateral symmetry
  • Have a separate mouth and anus
  • Have a notochord and a hollow, dorsal nerve tube for at least some period of their life cycle
  • Examples include mammals, birds, reptiles, amphibians and fish (also invertebrate sea squirts)
• Three domains of living organisms:

  • Eukarya – eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)
  • Archaea – prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)
  • Eubacteria – prokaryotic cells lacking a nucleus and consist of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)
• Taxonomic rank:

  1. Kingdom
  2. Phylum
  3. Class
  4. Order
  5. Family
  6. Genus
  7. Species