Organisms have different defence mechanisms to prevent themselves from being infected with a pathogen and fighting off the pathogen if they are infected.

In this topic you need to know about the following: -

  • The physical, chemical and biological defences that humans have.
  • How the immune system functions to protect us from disease.
  • How antibodies work.
  • Why we rarely get the same disease twice.

    • Use the arrows below to continue to revise.

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