Classification Systems

• what is taxonomy?

  the science of naming and classifying organisms within groups called taxa
• what are the groups organisms are classified into called?

  taxa
• what is systematics?


  the science of determining evolutionary relationships among organisms
• what is the classification system we use today called?

  the Linnaean system
• is taxonomy a science?

  yes
• is phylogeny a science?

  no
• what is the system called in which organisms are given two part scientific names in latin?

  Binomial nomenclature
• where does the binomial nomenclature name for organisms come from?


  the genus and the species
• what are the four characteristics for classifying organisms?

  morphological characters, fossil records, embryology and molecular analysis
• what are the two types of morphological characters?

  homologous and analogous
• what are homologous characters?

  characters which look the same because they have the same origin as they came from a common ancestor
• what are analogous characters?

  characters that look the same but do not have the same origin = this is called convergent evolution
• what is convergent evolution?

  Similar traits evolving independently.
• what is it called when functionally similar traits evolve independently?

  Convergent evolution
• what are the two types of homologous characters?

  primitive and derived
• what are primitive characters?

  shared traits within mammal groups
• what are derived characters?

  traits comparing mammals with other vertebrate groups
• what are the three schools of thought for classification?

  phonetic system, classic evolutionary system and the cladistic system
• what does the phonetic system involve?

  grouping organisms based on phenotypic similarities only without trying to reconstruct past evolutionary relationships
• what is the main problem with the phenetic system?

  it fails to distinguish between homologous and analogous characteristics
• what does the classic evolutionary and cladistic system involve?

  both group organisms based on similarities of characters which reflect their evolutionary relationships
• what is the difference between classic evolutionary systems and cladistic systems?

  classic looks at both primitive and derived characters, accepting both mono and paraphyletic groups, whereas cladistic looks at derived characters only, accepting only monophyletic groups
• what are the three types of taxa?

  monophyletic, paraphyletic and polyphyletic
• who are included in monophyletic taxa?

  ancestors and all descendants
• who are included in paraphyletic taxa?

  ancestors and not all of the descendants
• who are included in polyphyletic taxa?

  missing ancestors
• which types of taxa are recognised by modern systematics?

  monophyletic and paraphyletic
• as a phylogenetic tree is only a hypothesis of evolutionary relationships, how do we decided which of the potential predications is correct?

  we use the principle of parsimony
• what are the three methods we can use to add time to phylogenetic trees?

  radiometric dating, stratigraphy and molecular clocks
• how many domains are there?

  three
• what are the three domains?

  eukarya, Archaea and bacteria
• what characterises the Animalia kingdom?

  Multicellular organisms with eukaryotic cells, no cell walls, heterotrophic, cell differentiation, sexual reproduction and blastula stages of development in the embryo
• what are the three types of body cavities?

  coelomates, acoelomates and pesudeocoelomates
• what are coelomates?

  Animals with a true body cavity called a coelom and internal organs surrounded by mesoderm
• what are acoelmoates?

  Animals with no enclosed body cavity.
• what are pseudocoelomates?

  animals lined with mesoderm but no mesoderm surrounding the internal organs
• what can the coelomates be divided into?

  protostomes and deuterostomes
• what does differentiation between protostomes and deuterostomes depend on?

  how the embryo have developed
• what is an acoelomate?

  An organism without a body cavity.