Health and disease — Edexcel GCSE Biology
What health means, communicable and non-communicable diseases, and why one disease can make you more likely to get another.
Revision notes
3 short notes, in the order of the specification. Each one in short:
Health is a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity. This is the World Health Organization (WHO) definition. It means someone can have no disease and still not be healthy, for example a person who is physically fit but severely stressed and isolated.
A communicable disease is caused by a pathogen and can be passed from one organism to another, such as cholera, tuberculosis and malaria. A non-communicable disease is not caused by a pathogen and cannot be passed from one person to another, such as cardiovascular disease, many cancers and diseases linked to nutrition.
One disease can lead to another by making a person more susceptible. HIV destroys white blood cells, so people with HIV are more likely to develop tuberculosis. A disease can also damage barriers such as the skin, cause poor nutrition or lead to poor mental health. A correlation in data does not prove that one disease causes another.
Exam questions
4 exam-style questions (8 marks), each with its mark scheme.
Answer the questionsFlashcards
7 cards: flip them, mark what you knew, and practise the rest.
Practise the cardsMind map
The whole of health, disease and the development of medicines on one page, so you can see where this subtopic fits.
Open the mind mapPrint it
Free PDFs to print or save.
Quick check questions
Give the WHO definition of health.
Show answer
A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
What is the main difference between communicable and non-communicable diseases?
Show answer
Communicable diseases are caused by pathogens and can be passed on; non-communicable diseases cannot be passed on.
Explain why someone with HIV is more likely to get tuberculosis.
Show answer
HIV destroys white blood cells, so the immune system is weakened and cannot fight off other pathogens.
What does a positive correlation on a scatter diagram show?
Show answer
As one variable increases, the other also increases.
Frequently asked questions
What is the WHO definition of health?
The World Health Organization (WHO) defines health as a state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity. In an exam, include all three words: physical, mental and social. This means a person with no disease may still not be fully healthy.
Is heart disease communicable?
No, heart disease is a non-communicable disease. It is not caused by a pathogen and cannot be passed from one person to another; instead it is linked to several interacting factors, such as diet and smoking. Communicable diseases, such as cholera, tuberculosis and malaria, are caused by pathogens and can be passed on.
How can one disease lead to another?
One disease can lead to another by making a person more susceptible. HIV destroys white blood cells, weakening the immune system, so infections such as tuberculosis are more likely. Diseases that damage the skin or the lining of the airways let other pathogens in, and long-term physical illness can lead to depression or anxiety.
Does a correlation prove that one disease causes another?
No, a correlation does not prove that one disease causes another. A scatter diagram may show that as one disease becomes more common, so does another, but something else could be responsible for both. Data from a large, randomly chosen and representative sample is more reliable, but it still only supports a link.
Written and checked against the Edexcel GCSE Biology (1BI0) specification · Updated October 2026