natural selection

• Natural selection


  Survival of the fittest - animals that are better suited to the environment survive and those that are not die off
• Stages of natural selection

  1. Variation

  2. Natural selection

  3. Inheritance

  4. Evolution
• Variation


  • Naturally occurring differences within a species due to genetics and environment
• Evolution


  • Animals not suited to the environment die off, leaving the adapted ones to survive and reproduce
• Darwin and Wallace came up with the theory of evolution
• Evidence for evolution


  • Bacteria developing antibiotic resistance
  • Human fossils showing gradual changes
  • Pentadactyl limb in different animals
• Five kingdoms to classify living things

  • Animals
  • Plants
  • Fungi
  • Prokaryotes
  • Protists
• Three domain system


  • Archaea
  • Bacteria
  • Eukarya (complex multicellular organisms)
• Selective breeding


  Breeding parents with desired characteristics to produce offspring with those traits
• Selective breeding can reduce the gene pool and cause health problems
• Tissue culture


  Growing cells on a medium to clone plants or create specialized animal cells
• Genetic modification


  1. Extract gene from one organism

  2. Insert gene into plasmid vector

  3. Insert plasmid into target organism cell
• Genetic modification


  • Fast and easy but expensive, can cause health problems, gene could spread to environment