Ultraviolet radiation, X-rays and gamma rays all have frequencies higher than visible light. Explain why gamma rays are considered the most dangerous of these three types of electromagnetic radiation to living tissue.

Eduqas GCSE Physics — 6.1 Frequency range of the spectrum · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Gamma rays have the highest frequency of the three.

Higher frequency means higher energy.

The higher energy of gamma rays means they cause more ionisation in living cells and can penetrate deeper into tissue.

This ionisation can damage or destroy cells and DNA, leading to cell death or cancer.

Examiner tips

  • Use the exact sequence: highest frequency → higher energy → more ionisation → deeper penetration → cellular damage.
  • Show the causal chain clearly; examiners look for logical progression.
  • Mention DNA damage as the ultimate harmful effect.
  • Keep sentences concise and use technical terms (ionisation, DNA).

Common mistakes

  • Confusing frequency with wavelength; students sometimes say ‘shorter wavelength’ instead of ‘higher frequency’.
  • Failing to link higher energy to deeper penetration and ionisation.
  • Omitting the final consequence (cell death or cancer).

Mark scheme (4 marks)

  1. Gamma rays have the highest frequency of the three
  2. Higher frequency means higher energy
  3. The higher energy of gamma rays means they cause more ionisation in living cells / can penetrate deeper into tissue
  4. This ionisation can damage or destroy cells / DNA, leading to cell death or cancer

Key terms in this question

electromagnetic radiation · gamma rays

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