Seneca
Sign up

Causing Diseases

Biology: AQA GCSE Higher, topic 3.1.2

Spreading Disease

There are three ways an infectious disease can spread:

Direct contact

Direct contact

  • Some pathogens live on the surface of other organisms, such as the skin. If infected skin touches a surface, some of the pathogens can transfer from the infected skin to the surface.
  • The pathogen then spreads to other people who also touch that surface. Athlete's foot is spread in this way.
Water

Water

  • Some pathogens contaminate water supplies. Organisms drinking this contaminated water can be infected by pathogens.
  • Cholera is a disease spread in this way.
Air

Air

  • Some pathogens are released into the air inside droplets when an organism coughs or sneezes. These droplets can then be inhaled (breathed in) by other organisms.
  • The flu and common colds are spread in this way.

Test yourself on Causing Diseases

  • Two people share a towel after one of them has athlete's foot on their skin. Why might the second person become infected?

  • Why do cells infected by a virus eventually burst open?

  • A gardener gets a small cut on their hand and fungal spores from a plant infect the wound. What allows the fungal infection to spread into the surrounding skin?

  • How do fungi spread from an infected organism to a new host?

Practise this topic for free