Non-Communicable DiseasesAQA GCSE Biology: Revision notes
Section 1
What is health, and how do diseases interact?
Health is the state of physical and mental well-being. Disease is a major cause of ill health, and different types of disease can interact:
- Immune deficiency (e.g. HIV/AIDS) increases susceptibility to infectious disease
- Viruses living in cells can trigger cancers
- Immune reactions to pathogens can cause allergic reactions such as skin rashes and asthma
- Severe physical ill health can lead to mental ill health such as depression
Section 2
How do lifestyle factors affect non-communicable disease?
Non-communicable diseases have a large human and financial cost at individual, local, national and global levels. Lifestyle factors that increase the incidence of non-communicable disease include:
- Diet — e.g. high fat/sugar diets linked to obesity and Type 2 diabetes
- Alcohol — linked to liver and brain damage
- Smoking — linked to lung disease and cancer
These effects are seen at local, national and global levels, and interpreting incidence data (e.g. from scatter graphs) is a key skill.
'Linked to' or 'correlated with' does not always mean 'causes' — check whether a causal mechanism has actually been proven.
Section 3
Is every risk factor proven to cause disease?
A causal mechanism — a proven biological reason why X causes Y — has been established for some risk factors but not all:
| Causal mechanism proven | Example |
|---|---|
| Yes | Smoking causes lung disease and cancer; alcohol damages the liver and brain; smoking/alcohol harm unborn babies; ionising radiation is carcinogenic |
| Correlated, mechanism debated/complex | Diet, smoking and exercise affecting cardiovascular disease risk; obesity as a risk factor for Type 2 diabetes |
Section 4
What is cancer, and how do tumours differ?
Cancer results from changes in cells that lead to uncontrolled growth and division, forming a tumour.
- Benign tumours: grow but remain contained in one place, usually within a membrane, and do not invade other tissues
- Malignant tumours (cancers): invade neighbouring tissues and can spread via the blood to form secondary tumours elsewhere in the body
Both lifestyle risk factors (e.g. smoking, UV exposure) and genetic risk factors have been identified for various types of cancer.
Don't say 'benign tumours are harmless' — they can still be dangerous if they grow large enough to press on organs; they simply don't spread.
Must Know
- Health = physical and mental well-being; diseases can interact (e.g. immune deficiency increases infection risk)
- Non-communicable diseases are strongly linked to lifestyle factors: diet, alcohol, smoking
- A causal mechanism has been proven for some risk factors (e.g. smoking → lung cancer) but not all correlations
- Cancer = uncontrolled cell growth and division
- Benign tumours stay contained; malignant tumours invade tissues and spread via the blood
- Both lifestyle and genetic risk factors contribute to cancer risk
That's the notes covered.
Carry on to the next subtopic.