Explain why a liver cell and a muscle cell, despite containing the same genetic information, carry out different functions.

WJEC GCSE Biology (Wales) — 1.1.1 Cell structure and organisation · Explain · 4 marks · View as Markdown

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

All cells in the human body are produced by cell division from a single fertilised egg. Each cell therefore contains an identical set of genetic instructions. Yet cells in the body become specialised to perform particular roles.

Model answer (4 marks)

During development cells become specialised or differentiated.

In each cell type different genes are switched on (or off).

This results in different proteins being produced in each cell type.

The specific proteins present determine the structure and function of the cell, so a liver cell carries out detoxification and protein synthesis while a muscle cell carries out contraction.

Examiner tips

  • Use the word ‘different’ to link genes to proteins; mention ‘switched on/off’ to show regulation.
  • Show the chain: differentiation → gene expression → protein production → function.
  • Keep each point short and use the exact wording from the mark scheme.

Common mistakes

  • Confusing ‘gene expression’ with ‘DNA replication’ or ‘cell division’.
  • Failing to mention that the same DNA is present in all cells.
  • Giving a generic answer that does not link proteins to cell function.

Mark scheme (4 marks)

  1. During development cells become specialised / differentiated
  2. Different genes are switched on (or off) in different cell types
  3. This leads to different proteins being produced in each cell type
  4. The specific proteins present determine the structure and function of the cell

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