State the correct order of the levels of organisation in a multicellular organism, from smallest to largest, and define each level.

Cambridge International IGCSE Biology (0610) — 2.2 Levels of organisation · State · 4 marks · View as Markdown

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

Model answer (4 marks)

Cell – the smallest level, the basic building block of all living organisms.
Tissue – a group of similar (specialised) cells working together to carry out a specific function.
Organ – a group of (specialised) tissues working together to carry out a specific function.
Organ system – the largest level, a group of (related) organs working together to carry out functions in the body.

Examiner tips

Use the exact wording from the mark scheme for each definition.
List the levels in order: cell, tissue, organ, organ system.
Keep each definition brief but complete – no extra words.
Check UK spelling (e.g., ‘organisation’ if required).

Common mistakes

Mixing up the order of the levels.
Using vague terms like ‘group of cells’ without specifying ‘specialised’.
Adding unnecessary detail that distracts from the required definition.

Mark scheme (4 marks)

Cell is the smallest level and is defined as the basic building block of all living organisms
Tissue is the next level and is defined as a group of similar (specialised) cells working together to carry out a specific function
Organ is the next level and is defined as a group of (specialised) tissues working together to carry out a specific function
Organ system is the largest level and is defined as a group of (related) organs working together to carry out functions in the body

Key terms in this question

cell · organ