DP Biology (last assessment 2024)
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5.3 Classification of biodiversity

Description

Nature of science:
Cooperation and collaboration between groups of scientists—scientists use the binomial system to identify a species rather than the many different local names. (4.3)
Understandings:
  • The binomial system of names for species is universal among biologists and has been agreed and developed at a series of congresses.
  • When species are discovered they are given scientific names using the binomial system.
  • Taxonomists classify species using a hierarchy of taxa.
  • All organisms are classified into three domains.
  • The principal taxa for classifying eukaryotes are kingdom, phylum, class, order, family, genus and species.
  • In a natural classification, the genus and accompanying higher taxa consist of all the species that have evolved from one common ancestral species.
  • Taxonomists sometimes reclassify groups of species when new evidence shows that a previous taxon contains species that have evolved from different ancestral species.
  • Natural classifications help in identification of species and allow the prediction of characteristics shared by species within a group.
Applications and skills:
  • Application: Classification of one plant and one animal species from domain to species level.
  • Application: Recognition features of bryophyta, filicinophyta, coniferophyta and angiospermophyta.
  • Application: Recognition features of porifera, cnidaria, platyhelmintha, annelida, mollusca, arthropoda and chordata.
  • Application: Recognition of features of birds, mammals, amphibians, reptiles and fish.
  • Skill: Construction of dichotomous keys for use in identifying specimens.
Guidance:
  • Archaea, eubacteria and eukaryote should be used for the three domains.
  • Members of these domains should be referred to as archaeans, bacteria and eukaryotes.
  • Students should know which plant phyla have vascular tissue, but other internal details are not required.
  • Recognition features expected for the selected animal phyla are those that are most useful in distinguishing the groups from each other and full descriptions of the characteristics of each phylum are not needed.
  • Viruses are not classified as living organisms.
 International-mindedness:
  • There are international codes of nomenclature and agreements as to the principles to be followed in the classification of living organisms.
Theory of knowledge:
  • The adoption of a system of binomial nomenclature is largely due to Swedish botanist and physician Carolus Linnaeus (1707–1778). Linnaeus also defined four groups of humans, and the divisions were based on both physical and social traits. By 21st-century standards, his descriptions can be regarded as racist. How does the social context of scientific work affect the methods and findings of research? Is it necessary to consider the social context when evaluating ethical aspects of knowledge claims?

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