AQA GCSE Biology

Revision Notes

3.1.2 Viral Diseases

  • 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 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 (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

Exam 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.

Author: Jenna

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.

Join Save My Exams

Download all our Revision Notes as PDFs

Try a Free Sample of our revision notes as a printable PDF.

Join Now