Biology 3.6 - Evolution of Species

• What is mutation?

  A random change in an organisms genetic material. They are spontaneous and the only source of new alleles
• What is an advantageous mutation?

  Mutations that increase the organisms chance of survival and reproduction.
• What are neutral mutations?

  These mutations are neither beneficial or harmful to an organism.
• Advantageous trait example?

  Lactose tolerance in humans
• Neutral mutation example?

  Attached/Detached earlobes
• Disadvantage mutation meaning?

  These are mutations which decrease the selective advantage.
• Disadvantage mutation example?

  Down syndrome / Cystic Fibrosis
• When does natural selection occur?

  When there are selection pressures and individuals best adapted to the environment survive to reproduce and pass on their favourable alleles.
• What is stage one in natural selection?

  Organisms produce too many offspring and the environment cannot sustain them
• What is stage two in natural selection?

  Struggles for survival now follow due to competition or predation
• What is stage three in natural selection?

  Although being the same species, some variation is shown in alleles
• What is stage four in natural selection?

  Those with alleles best suited to their environment have a better chance of surviving and reproducing
• What is the final stage of natural selection?

  This process repeats over several generations until only the organisms with the best suited alleles survive.
• Define mutation?

  A random change in genetic material