3.1.3

Other Pathogens

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Bacteria

Bacteria are small living cells that either damage cells directly or by producing toxins (poisons). Bacteria can reproduce rapidly in warm, moist conditions that have a good supply of oxygen. Some examples of bacterial diseases:

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Salmonella

  • If food has not been cooked properly or has been prepared in unhygienic conditions, then we may ingest (eat) Salmonella bacteria that cause food poisoning.
  • The bacteria release toxins (poisons), causing fever, stomach pain, vomiting and diarrhoea.
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Gonorrhoea

  • Gonorrhoea is a sexually transmitted disease.
  • Its symptoms include pain when urinating and a thick yellow or green discharge from the vagina or penis.
  • Barrier methods of contraception, such as condoms, can be used to stop the bacteria spreading from person to person.

Fungi

Fungi are unicellular (have one cell) or multicellular organisms that each have bodies made up of hyphae (thread-like structures). The hyphae are able to grow and penetrate tissues, such as human skin or the surface of plants. The hyphae produce spores that can spread to other plants and animals. An example of a fungal disease is:

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Rose black spot

  • Rose black spot can be spread in water or in the air (wind).
  • It causes purple or black spots on the leaves of rose plants.
  • Eventually, the leaves discolour and fall off. This makes it harder for plants to photosynthesise and plant growth slows.
  • Removing and destroying discoloured leaves and using fungicides can treat affected plants.

Protists

Protists are single-celled eukaryotic organisms (they have a nucleus). Lots of protists are parasites. This means that they live on or inside other organisms. They are often transferred to the host organism by a vector, such as an insect or mosquito. An example of a disease caused by a protist is:

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Malaria

  • Malaria is spread by the female anopheles mosquito (a vector).
  • If a mosquito is carrying malaria, then it transfers the infection into a person’s bloodstream when it bites them.
  • Malaria leads to recurring and severe fevers, which can cause death.

Jump to other topics

1Cell Biology

2Organisation

2.1Principles of Organisation

2.2Enzymes

2.3Circulatory System

2.4Non-Communicable Diseases

2.5Plant Tissues, Organs & Systems

3Infection & Response

4Bioenergetics

5Homeostasis & Response

6Inheritance, Variation & Evolution

7Ecology

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