AQA A-Level Biology: Characteristics of Tumours and Cancer Development — mark scheme explained

The question

Mark scheme, decoded

How the examiner actually awards the marks on this topic.

Gradora's own decode of the marking approach — not the exam board's published mark scheme.

Model answer

A full-mark response to the question above, worked through step by step.

⏱Timing: Allocate approximately 5-7 minutes per question to ensure you have enough time to carefully read the problem, provide detailed answers, and check your work.

1. Define benign tumours.1 mark
   Benign tumours are non-cancerous growths that do not spread to other parts of the body, grow slowly, have well-defined borders, and rarely recur after surgical removal.
2. Define malignant tumours.1 mark
   Malignant tumours are cancerous growths that can spread (metastasize) to other parts of the body, grow rapidly, have irregular borders, and often recur after surgical removal.
3. Compare the characteristics.2 marks
   Benign tumours are generally less threatening and easier to treat, while malignant tumours are more aggressive and can be life-threatening due to their ability to spread.

Final answer: Benign tumours are non-cancerous, grow slowly, have well-defined borders, and rarely recur. Malignant tumours are cancerous, can spread, grow rapidly, have irregular borders, and often recur.

✓Work through every step correctly and you earn all 4 marks.

Common mistakes

• Confusing benign and malignant tumours.

  Why it happens: Students may mix up the characteristics of benign and malignant tumours, leading to incorrect descriptions in their answers.

  Fix: Always remember that benign tumours are non-cancerous, grow slowly, have well-defined borders, and rarely recur. Malignant tumours are cancerous, can spread, grow rapidly, have irregular borders, and often recur.

• Misunderstanding the roles of oncogenes and tumour suppressor genes.

  Why it happens: Students may confuse the functions of oncogenes and tumour suppressor genes, leading to incorrect explanations of how they contribute to cancer development.

  Fix: Oncogenes are mutated versions of proto-oncogenes that cause uncontrolled cell proliferation. Tumour suppressor genes normally prevent cells from dividing too rapidly or uncontrollably. When these genes are mutated or inactivated, they can no longer perform their protective function.

• Failing to recognize the significance of abnormal methylation.

  Why it happens: Students may not fully understand how hypomethylation and hypermethylation contribute to cancer development, leading to incomplete or incorrect answers.

  Fix: Hypomethylation can activate oncogenes, promoting cell proliferation. Hypermethylation can silence tumour suppressor genes, leading to a loss of their protective function. Both processes are important in cancer development.

• Not understanding the role of oestrogen in breast cancer.

  Why it happens: Students may not fully grasp how increased oestrogen concentrations contribute to the development of breast cancer, leading to vague or incorrect explanations.

  Fix: Increased endogenous and exogenous oestrogen levels can promote the growth of breast cancer cells by binding to oestrogen receptors. This is associated with higher risk in women who start menstruating early or enter menopause late, and exposure to external sources of oestrogen.

• Failing to evaluate evidence effectively.

  Why it happens: Students may struggle to analyze data or research findings related to genetic and environmental factors in cancer, leading to weak or unsupported conclusions.

  Fix: Practice analyzing data and drawing conclusions based on the evidence provided. Look for patterns and trends in the data that support your explanations.

• Not providing clear and concise explanations.

  Why it happens: Students may provide vague or overly complex answers, leading to a lack of clarity and precision.

  Fix: Practice writing clear and concise explanations that demonstrate a deep understanding of the topic. Use specific examples and key terms to support your answers.

Where the marks go

The question types you’ll meet on this topic and the marks each one carries — so you know what to expect and where to focus.

Question types and mark tariffs are Gradora’s guidance based on how this topic is typically examined — not the board’s official paper structure.

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