Classification and biodiversity

• What is classification in biology?

  Organization of living things into groups
• What is the main aim of classification?

  To group organisms by evolutionary relationships
• How is classification structured?

  It is hierarchal with decreasing group sizes
• What does phylogenetic classification imply?

  Organisms in the same group are closely related
• What is a taxon?

  A group in biological classification
• How many kingdoms do all living organisms belong to?

  Five kingdoms
• What is the largest taxonomic group?

  Kingdom
• What is the smallest taxonomic group?

  Species
• What is the mnemonic for the taxonomic hierarchy?

  • K: Kingdom
  • P: Phylum
  • C: Class
  • O: Order
  • F: Family
  • G: Genus
  • S: Species
• What does the tentative nature of classification mean?

  It can change with new information
• What significant change in classification occurred in 1977?

  Studies suggested three domains
• What is a domain in biological classification?

  A larger taxon than a kingdom
• What are the three domains of life?

  Eubacteria, Archaea, Eukarya
• What characterizes Eubacteria?

  They are 'true' bacteria and prokaryotic
• What are Archaea known for?

  Being prokaryotic extremophiles
• What does Eukarya encompass?

  All eukaryotic organisms
• What are extremophiles?

  Organisms living in harsh environmental conditions
• What are thermophiles and psychrophiles?

  Extremophiles that live in extreme temperatures
• What environments do halophiles thrive in?

  Areas with high salinity
• What conditions do extremophiles adapt to?

  High/low temperatures, acidity, salinity
• How do the three domains differ from each other?

  They represent distinct evolutionary lineages
• What does the theory of evolution suggest about organisms?

  They share a common ancestor.
• What indicates that organisms have diverged from a common ancestor earlier?

  More differences between the organisms.
• What are homologous structures?

  Structures with a common evolutionary origin.
• What is an example of a homologous structure?

  The pentadactyl limb of vertebrates.
• What does divergent evolution refer to?

  Development of differences from a common ancestor.
• What are the functions of the pentadactyl limb in different vertebrates?

  • Grasping (human arm)
  • Walking (horse leg)
  • Swimming (whale flipper)
  • Flying (bat wing)
• What is convergent evolution?

  Independent development of similar features.
• What are analogous structures?

  Structures with similar function but different origins.
• How do DNA sequences help assess relatedness?

  More similarity indicates closer relatedness.
• What is DNA hybridization?

  Comparing DNA base sequences of species.
• What percentage of DNA do humans and chimpanzees share?

  At least 96%
• What does the amino acid sequence reflect?

  The degree of relatedness between species.
• How can immunology be used to assess relatedness?

  By comparing coagulation of antigens and antibodies.
• What is the morphological definition of a species?

  Organisms that look very similar.
• What is sexual dimorphism?

  Differences between male and female organisms.
• Why is the reproductive definition of a species challenging for some scientists?

  It requires organisms to breed successfully.
• What is taxonomy?

  The identification and naming of organisms.
• What is the binomial system?

  A two-name system for naming organisms.
• Who introduced the binomial system?

  Linnaeus