Viral Diseases (AQA GCSE Biology: Combined Science)

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Viruses: Basics

  • There are many common diseases caused by viruses; for example, the common cold and the flu are caused by viruses
  • Viruses do not fulfil the 7 life processes, therefore, they are not usually classified as living organisms
    • Viruses do not have nuclei, organelles, or cytoplasm like cells do, and so they have no way to monitor or create change in their internal environment

  • Viruses reproduce rapidly by inserting their genetic material into host cells and creating new protein capsules to build new viral particles
  • Once many copies have been made, the host cell may burst open releasing the viral particles which can go on to infect other cells

Measles

  • Measles is a highly contagious and a potentially serious viral infectious disease that can be fatal if complications arise
  • Measles is most often seen in children – most young children are vaccinated against it

 

Measles table

Measles characteristics table, downloadable IGCSE & GCSE Biology revision notes

HIV

  • HIV (Human Immunodeficiency Virus) is a virus that can eventually lead to Acquired Immunodeficiency Syndrome (AIDS)

HIV table

HIV table, downloadable IGCSE & GCSE Biology revision notes

Tobacco Mosaic Virus

  • Tobacco mosaic virus (TMV) was the first virus to be isolated by scientists
  • It is a widespread plant pathogen that infects about 150 species of plants including tomato plants and cucumbers

TMV table

Tobacco Mosaic Virus table, downloadable IGCSE & GCSE Biology revision notes

Examiner Tip

Know the symptoms and how the pathogen causing each disease is spread. Typically this topic appears as data analysis questions in the exam where you may be given a graph to analyse and interpret.

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Lára

Author: Lára

Expertise: Biology Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.