DP IB Biology: HL

Revision Notes

Syllabus Edition

First teaching 2014

Last exams 2024


11.1.5 Zoonosis

Test Yourself


  • Some diseases are species specific whilst others can cross species barriers to infect multiple different species
  • Species-specific disease may be unable to cross the species barrier for many reasons:
    • If a species does not possess the necessary receptors to be at risk of infection
    • If the body temperature of the organism doesn't reach temperatures required for the development of the disease
  • Zoonotic diseases are those which can cross the species barrier from animal to human
  • This is a growing global concern due to the close relationships between humans and animals meaning the disease may be difficult to control and eradicate
  • This may potentially lead to pandemics such as that caused by COVID-19
  • Animal products may also be affected by zoonotic disease which poses a further issue
  • Some zoonotic diseases can initially emerge from animal populations before developing into human only strains e.g. HIV

Table to show some examples of  human only and zoonotic diseases


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Author: Ruth

Ruth graduated from Sheffield University with a degree in Biology and went on to teach Science in London whilst also completing an MA in innovation in Education. With 10 years of teaching experience across the 3 key science disciplines, Ruth decided to set up a tutoring business to support students in her local area. Ruth has worked with several exam boards and loves to use her experience to produce educational materials which make the mark schemes accessible to all students.