selection

• natural selection

  • genetic variation within populations
  • production of many offspring
  • struggle for survival, including competition for resources
  • greater chance of reproduction by individuals that are better adapted to the environment - these individuals pass on alleles to the next generation
• adaptation: the process, resulting from natural selection, by which populations become more suited to their environment over many generations
• antibiotic resistance

  • when antibiotics are used, most bacteria of a certain strain dies
  • but some bacteria may have a genetic mutation that makes them resistant to antibiotics
  • resistant bacteria survive and reproduce quickly, leading to a large number of bacteria with the same resistance
  • consequently, antibiotics become ineffective due to widespread of resistant bacteria