HL 1 Biology

5.5a Classification


Binomial nomenclature: naming organisms

  • first name is the genus; a group of species that share certain characteristics
  • second name is the species/specific name 
  • Rules:
      • genus name begins with a CAPITAL letter and species name with a lower-case letter
      • in typed/printed text binomial is in italics
      • after binomial is used once in the text , it can be abbreviated (e.g. L. borealis)
      • earliest published name for a species (from 1753) is the right one

<<The Hierarchy of Taxa>>

Taxa: groups species are arranged/classified in

  • group of similar organisms grouped into species
  • every species classified into a genus
  • genera are grouped into families
  • families grouped into orders
  • orders into classes
  • classes grouped into phylum
  • and phyla into kingdom
  • members of the taxon should have a common ancestor

<<Dichotomous Keys>>

  • hierarchy of taxa help identify organism + to investigate a community
  • keys are used to help assign a species to the correct group; needed the lower you go down taxa
  • dichotomous key: consists of a numbered series of pairs of description
  • each pair of descriptions lead to another numbered pair of descriptions in the key or to identification

<<Plant Classification>>

  • plants classified together in one kingdom
  • in life cycle, male + females gametes formed together
  • the way embryo developes depends on the type of plant it is
  • different types of plants put into phyla
  • main phyla: angiospermophyta, coniferophyta, filicinophyta, bryophyta


Classifying Cartilaginous Fish (p. 206)

1) Kingdom: Animalia

2) (a) Two in the middle and two in the bottom left and right

(b) i) Different species because they have different colors and design characteristics on their backs.

ii) Same families because they have the same structures and are the same type of fishes.

c) Large triangular back fins, long tail with slits in the bottom and eyes on the top of its head.

2) The four fish are split into two orders as the fish in the middle on the very right has four distinct fins yet the proportion of them are very big compared to the other three fishes on the top and middle bottom. The Other three fishes have smaller fins and eyes on the side of their head, unlike the middle right fish with eyes on the top of its head.

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