4B

• biodiversity


  a measure of the variety of living organisms and their genetic differences
• evolution


  process by which natural selection acts on variation to bring about adaptations and eventually speciation
• taxonomy


  the science of describing, classifying and naming organisms
• morphology


  the study of the form and structure of the organisms
• analogous features


  features that look similar or have a similar function, but are not from the same biological origin
• homologous structures


  structures that genuinely show common ancestry
• domains


  the three largest classification categories: Eukaryota, Bacteria, Archaea
• kingdom


  the classification category smaller than domains
• There are 6 kingdoms: Archaebacteria, Eubacteria, Protista, Fungi, Plantae, Animalia
• phylum


  a group of classes that all share common characteristics
• class


  a group of orders that all share the same characteristics
• order


  a group of families that all share the same characteristics
• family


  a group of genera that all share the same characteristics
• genus


  a group of species that all share the same characteristics
• species


  a group of closely related organisms that are all potentially capable of interbreeding to produce fertile offspring
• Archaea


  domain made up of bacteria-like prokaryotic organisms found in many places, including extreme conditions and the soil, they are thought to be early relatives of the eukaryotes
• Archaebacteria


  ancient type of bacteria found in many different environments
• Eubacteria


  true bacteria (prokaryotic organisms)
• Protista


  kingdom in the 6 kingdom system that contains all single celled organisms, green and brown algae, and slime moulds
• Fungi


  eukaryotic kingdom of heterotrophs with chitin in their cell walls
• Plantae 


  a mainly eukaryotic kingdom containing mosses, liverworts, ferns, gymnosperms, and angiosperms
• Animalia


  a mainly heterotrophic eukaryotic kingdom including all the invertebrates and vertebrates
• morphological species model


  a species definition based solely on the appearance of the organism observed
• sexual dimorphism


  describes species where there is a big difference between the appearance of the male and female
• molecular phylogeny


  analysis of the genetic material of organisms to establish their evolutionary relationships
• ecological species model


  species definition based on the ecological niche occupied by an organism
• mate-recognition species model


  species definition based on unique fertilisation systems, including mating behaviour
• genetic species model


  species model based on DNA evidence
• DNA sequencing


  process by which the base sequences of all or part of an organism is worked out
• DNA profiling


  process by which non-coding areas of DNA are analysed to identify patterns
• gel electrophoresis


  method of separating fragments of proteins or nucleic acids based on their electrical charge and size
• phylogenetic tree


  model used to show the relationship between different groups of organisms
• endosymbionts


  organisms that live inside the cells or bodies of another organism
• Monera


  kingdom in the 5 kingdom system that contains Archaea and Eubacteria
• extremophiles


  bacteria that can survive extreme conditions of heat, cold, pH, salinity and pressure
• Earth's biodiversity is reducing, which may affect the future health of the planet.
• Reasons for classification:

  • internationally recognised for easier communication
  • identifies different groups of organisms
  • monitors changes in the populations of different types of organisms
  • shows how different organisms are related, which makes ancestral relationships clear
• aim of taxonomy: group organisms to accurately identify them and represent their ancestral relationships
• Taxonomy used to be based solely on morphology, as analogous features were used to classify organisms, but the features may not have the same biological origin. Now, homologous features are used as they show common ancestry.
• Carolus Linnaeus - made the first scientifically devised classification system