Taxonomy- AS revision

Basics of taxonomy and methods of comparing organisms

  • Created by: Sazz
  • Created on: 31-05-09 17:22

Taxonomic Heirarchy








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Useful for- studying evolution, studying biology (can group organisms rather than studying every one), identifying unknown organisms

Members of the same species are similar to each other in characteristics and can breed to produce fertile offspring

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Types of Classification

Artificial Classification- Grouping organisms by features that are useful at the time eg. number of legs/wings/size

Natural Classification- Grouping organisms based on evolutionary relationships

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Comparing organisms 1

DNA Hybridisation

  • DNA from 2 organisms is separated into single strands
  • One organism's DNA is radioactively marked
  • DNA is mixed and cooled so it reforms into double helixs
  • Strands that are 50% radioactive are hybrids (half DNA from each organism)
  • Hybrid strands heated in stages to test for strength
  • Similar organisms= More complimentary base pairs= more hydrogen bonds= more strength
  • Therefore a higher splitting temperature means organisms are closely related
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Comparing Organisms 2

Immunology Comparisons

  • Proteins from one species are injected into another
  • The second species produces antibodies specific to antigen sites on the protein
  • Proteins extracted from second species and mixed with that of a third species
  • Antibodies respond to antigens and produce a precipitate
  • More precipitate= third species more similar to first

Courtship Behaviour

  • Used so species can recognise members of the same species that are capable of and receptive to breeding.
  • Forms a pair bond
  • The same between members of the same species but differs between species
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