Species and Taxonomy

• What is a species?


  A group of organisms that can interbreed to produce fertile offspring
• Suggest why two different species are unable to produce fertile offspring:

  • Different species have different chromosome numbers -> offspring may have odd chromosomes number
  • So homologous pairs can't form -> meiosis can't occur to produce gametes
• Explain why courtship behaviour is a necessary precursor to successful mating:

  • Allows recognition of members of same species -> so fertile offspring produced
  • Allows attraction / recognition of opposite sex
  • Stimulates / synchronises mating / production / release of gametes
  • Indicates sexual maturity / fertility
  • Establishes a pair bond to raise young
• Describe a phylogenetic classification system:

  • Species arranged into groups, called taxa, based on evolutionary origins and relationships
  • Uses a hierarchy:

  -Smaller groups are placed within larger groups

  -No overlap between groups
• Name the taxa in the hierarchy of classification:

  • Domain
  • Kingdom
  • Phylum
  • Class
  • Order
  • Family
  • Genus
  • Species
• How is each species universally identified?

  A binomial consisting of the name of the genus and species e.g. Homo sapiens
• Suggest and advantage of binomial naming:

  Universal so no confusion as many organisms have more than one common name
• Describe one advancement that have helped to clarify evolutionary relationships between organisms:

  Advances in genome sequencing -> allowing for comparison of DNA base sequences

  • More differences in DNA base sequences -> more distantly related / earlier common ancestor
  • As mutations build up over time
• Describe one advancement that have helped to clarify evolutionary relationships between organisms:?

  Advances in immunology -> allowing comparison of protein tertiary structure

  • Higher amount of protein from one species binds to antibody against the same protein from another species -> more closely related / more recent common ancestor
  • As indicates a similar amino acid sequence and tertiary structure
  • So less time for mutations to build up