Explain how cells are organised into different levels of organisation in a multicellular organism, naming each level in the correct order from smallest to largest.

Edexcel GCSE Biology (1BI0) — 1.2 Levels of organisation · Explain · 4 marks · View as Markdown

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

Model answer (4 marks)

Cells are the smallest level of organisation and are the basic structural and functional unit.
A group of similar cells working together forms a tissue.
Different tissues working together form an organ.
Organs working together form an organ system, and organ systems work together to form an organism.

Examiner tips

  • Use the exact sequence: cell → tissue → organ → organ system → organism.
  • Show the hierarchy clearly, e.g. by numbering or using arrows.
  • Mention that cells are the basic unit before moving to higher levels.
  • Use the wording from the mark scheme to avoid missing points.

Common mistakes

  • Mixing up the order (e.g. organ before tissue).
  • Omitting the smallest level (cells).
  • Using vague terms like ‘body’ instead of ‘organism’.

Mark scheme (4 marks)

  1. Cells are the smallest level of organisation / cells are the basic structural and functional unit
  2. A group of similar cells working together forms a tissue
  3. Different tissues working together form an organ
  4. Organs working together form an organ system, and organ systems work together to form an organism

Key terms in this question

cell · organ · organism · multicellular

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