Cancer
Build confidence in Cancer for GCSE Biology with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. Cancer is the result of uncontrolled cell division that forms tumours; make sure you can distinguish benign from malignant tumours.
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Topic overview
Cancer results from changes in cells that lead to uncontrolled growth and division. The result is a mass of abnormal cells called a tumour.
Benign tumours grow in one place, contained within a membrane, and do not invade other tissues. They are not usually dangerous unless they press on an organ. Malignant tumours are cancers: their cells invade neighbouring tissues and can spread in the bloodstream to form secondary tumours elsewhere.
Risk factors include smoking, obesity, ultraviolet exposure, viral infection and inherited genetic factors. Some cancers therefore have lifestyle causes, and some are genetic, and questions may ask you to distinguish these.
Revision notes
Benign and malignant tumours
Benign tumours are contained within a membrane and do not invade other parts of the body.
Malignant tumour cells are cancers: they invade neighbouring tissues and spread through the blood to form secondary tumours. This ability to spread is what makes them dangerous.
The cause
Cancer arises from changes in the cells that cause uncontrolled cell growth and division.
The normal controls on the cell cycle break down, so cells continue dividing when they should not, producing a tumour.
Risk factors
Lifestyle: smoking, obesity, ultraviolet exposure and alcohol. Viral: some viruses living in cells trigger cancers.
Genetic: inherited faulty genes increase risk for some cancers. A person may have several risk factors, and they can combine.
Key points
- Cancer is caused by uncontrolled cell division.
- A tumour is a mass of abnormal cells.
- Benign tumours stay in one place within a membrane.
- Malignant tumours invade tissues and spread in the blood.
- Secondary tumours form where cancer cells have spread.
- Risk factors include smoking, obesity, UV, viruses and genetics.
Worked examples
Example 1
State two differences between a benign and a malignant tumour. [2 marks]
Model answer
A benign tumour is contained within a membrane and stays in one place, whereas a malignant tumour invades neighbouring tissues (1 mark). Malignant tumour cells can also spread in the bloodstream to form secondary tumours, which benign tumours cannot do (1 mark).
Example 2
Explain what causes a tumour to form. [2 marks]
Model answer
Changes in the cells cause uncontrolled growth and division (1 mark), so cells continue to divide when they should not, producing a mass of abnormal cells (1 mark).
Example 3
Give one lifestyle risk factor and one non-lifestyle risk factor for cancer. [2 marks]
Model answer
Lifestyle: smoking, obesity or ultraviolet exposure (1 mark). Non-lifestyle: inherited faulty genes or infection by certain viruses (1 mark).
Common mistakes
Saying all tumours are cancer.
Only malignant tumours are cancers. Benign tumours are not.
Saying benign tumours are always harmless.
They can be dangerous if they press on an organ, though they do not spread.
Forgetting secondary tumours.
The ability to spread and form secondary tumours is the key feature of malignancy.
Listing only lifestyle risk factors.
Genetic and viral factors are also examinable.
Exam tips
- Distinguish benign from malignant precisely.
- Use the term secondary tumour when describing spread.
- Give both lifestyle and genetic risk factors when asked for a range.
- Say uncontrolled cell division when explaining the cause.
Key terms
- Tumour
- A mass of abnormally dividing cells.
- Benign
- A tumour contained in one place that does not invade other tissues.
- Malignant
- A cancerous tumour that invades tissues and can spread.
- Secondary tumour
- A tumour formed where cancer cells have spread to a new site.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.