Classification

• Classification

  Organising Living Organisms into Groups
• Looking at the similarities and differences between organisms allows us to classify them into groups
• Scientists have been classifying organisms for thousands of years, but the classification methods have changed over time
• There are two different classification systems: artificial and natural
• Artificial Classification Systems

  • Use observable features to place organisms into groups
• Observable features used in artificial classification systems

  • Whether they lay eggs, can fly, can cook a mean chilli
• Artificial classification systems are used to make keys for easy identification and grouping of organisms, but they are no longer seen as the best way to classify organisms
• Natural Classification Systems


  • Use evolutionary relationships to sort organisms
• In natural classification systems, living things are divided into five kingdoms (e.g. the plant kingdom, the animal kingdom)
• In natural classification systems, organisms are subdivided into smaller groups: phylum, class, order, family, genus, species
• Species are groups that contain only one type of organism and are defined as a group of similar organisms able to reproduce to give fertile offspring
• Developments in biology, such as improvements in technology like microscopes and DNA sequencing, lead to improvements in classification
• DNA sequencing is used in molecular phylogenetics to determine how closely related organisms are by comparing the sequence of DNA bases
• The more similar the DNA sequence between species, the more closely related they are. For example, human and chimpanzee DNA have about 94% similarity