Bacterial Diseases (AQA GCSE Biology)

Revision Note

Test Yourself
Lára

Author

Lára

Expertise

Biology Lead

Bacteria: Basics

  • Bacterial pathogens are cells that can infect plants and animals, causing disease
  • Not all bacteria are harmful (so not all bacteria are pathogens) – both the skin and large intestine, in particular, are home to hundreds of different bacterial species that play a vital role in maintaining our health
    • Bacteria on the skin act as competitors to harmful pathogens
    • Bacteria in the large intestine digest substances we can’t in food (such as cellulose) and provide essential nutrients (such as Vitamin K)

  • Bacterial pathogens produce toxins that cause damage to cells and tissues directly
  • In certain optimum conditions, some bacteria can reproduce rapidly (with the fastest being once every 20 minutes for some species of coli)
    • Optimum conditions usually involve warmth, moisture and a supply of nutrients

Bacteria Growth curve, downloadable IGCSE & GCSE Biology revision notes

The graph shows the exponential growth of bacteria due to binary fission

Salmonella

  • Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions
  • It is found in the gut of many different animals

Salmonella table

Salmonella table, downloadable IGCSE & GCSE Biology revision notes

Gonorrhoea

  • Gonorrhoea is a sexually transmitted disease (STD) – these diseases are also called sexually transmitted infections (STI)
  • In 2018 it had the largest increase (26%) of infections in the UK (a total of 56,259 cases!). It was the cause of 13% of diagnosed STDs

Gonorrhoea table

Gonorrhoea 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.

You've read 0 of your 0 free revision notes

Get unlimited access

to absolutely everything:

  • Downloadable PDFs
  • Unlimited Revision Notes
  • Topic Questions
  • Past Papers
  • Model Answers
  • Videos (Maths and Science)

Join the 80,663 Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Lára

Author: Lára

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.