evolution

• Natural selection


  There is a genetic variation for a characteristic within a population. Individuals with a species that are better adapted to the environment for a characteristic survive + reproduce. The advantageous gene for the characteristic is inherited by the offspring.
• Natural selection


  1. Genetic variation

  2. Individuals with advantageous characteristics survive and reproduce

  3. Advantageous genes inherited by offspring
• Charles Darwin's theory of evolution by natural selection


  • Challenged the idea that god created every species, therefore went against religious beliefs
  • Insufficient evidence at the time
  • Mechanism of inheritance and knowledge of DNA + genes not yet discovered
• Lamarck's theory of evolution

  Organisms acquired a characteristic in their lifetime. Changes occurred to the organism to develop the characteristic. The offspring then inherit the characteristics.
• Species


  A group of similar organisms that can interbreed to give fertile offspring
• Speciation


  The development of a new species
• Speciation


  1. Isolation

  2. Genetic variation

  3. Natural selection

  4. Speciation
• Fossils


  Remains of organisms from millions of years ago, commonly found in rocks. Can tell us how little or how much different organisms have changed over time.
• How fossils may be formed

  • Organism dies and gets buried in sediment, soft parts decay and other parts replaced by minerals
  • Preserved parts of organisms where 1 or more conditions needed for decay are absent
  • Preserved traces of organisms such as footprints, burrows and root traces
• The fossil record is incomplete because early life-forms were soft-bodied and have completely decayed, and some fossils have been destroyed by geographical activity
• Antibiotic resistance


  Bacteria can develop / evolve to acquire antibiotic resistance by natural selection
• Antibiotic resistance in bacteria

  1. Random mutations occur in genes

  2. Bacteria with resistant gene have an advantage

  3. Bacteria with resistant gene survive and reproduce

  4. Bacteria population become more resistant
• Factors increasing chances of bacteria becoming resistant


  • Doctor's prescribing antibiotics unnecessarily
  • Patients not completing their course of antibiotics
  • Agricultural use of antibiotics (too much)
• 1. domain system proposed by Carl Woese


  • Archaea - primitive bacteria living in extreme conditions
  • Bacteria - true bacteria
  • Eukaryota - includes fungi, plants, animals and protists