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  • Classification
    • The concept of a species
      • A species is the basic unit of classification. A definition of a species is not easy but members of a single species have certain things in common
      • They are similar to one another but different from members of other species - they have very similar genes and therefore closely resemble one another physically and biochemically
        • They have similar patterns of development and similar immunological features and they occupy the same ecological niche
      • They are capable of breeding to produce living, fertile offspring. They are therefore able successfully to produce more offspring.
    • Naming species - the binomial system
      • At one time scientists gave new organisms a name that described their features e.g. black bird.
        • This resulted in the same name being used in a different part of the world for a completely different species.
      • Organisms are identified by two names and hence the system is called the binomial system
      • It is a universal system based upon Latin or Greek names
      • The first name, called the generic name, denotes the genus to which the organism belongs. This is the equivalent to the surname used to identify people
      • The second name, called the specific name, denotes the species to which the organism belongs.
      • There are three rules when using this system
        • The names are printed in italics or if handwritten they are underlined to show they are scientific names
        • The first letter of the generic name is in upper case but the specific name is all in lower case
        • If the species name is not known, it can be written as sp.
    • Grouping species together - the principles of classification
      • Sort organisms into manageable groups. This allows for better communication between scientists
      • This process is known as classification, while the theory and practice of biological classification is called taxonomy
      • There are two types of biological classification, each used for a different purpose
        • Artificial classification divides organisms according to differences that are useful at the time. Such features may include colour, size, number of legs, leaf shape etc.
          • These are described as analogous characteristics where they have the same function but do not have the same function but do not have the same evolutionary origins.
        • Natural classification is based upon the evolutionary relationships between organisms and their ancestors, classifies species into groups using shared features derived from their ancestors and they arrange the groups into a hierarchy in which the groups are contained within larger composite groups with no overlap
          • Relationships in a natural classification are based upon homologous characteristics. These have similar evolutionary origins regardless of their functions in the adult of the species
    • Organising the groups of species - taxonomy
      • Each group within a natural biological classification is called a taxon. Taxonomy is the study of these groups and their positions in a hierarchical order, where they are known as taxonomic ranks.
      • Kindom
        • Phylum
          • Class
            • Order
              • Family
                • Genus
                  • Species


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