Describe the four levels of organisation in a multicellular organism, starting from the simplest level.

AQA GCSE Biology (8461) — 4.2.1 Principles of organisation · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

1. Cell – the basic building block of life.
2. Tissue – a group of similar cells that perform a specific function.
3. Organ – an aggregation of tissues that carry out a particular function.
4. Organ system – a group of organs that work together to perform a complex function in the organism.

Examiner tips

Use the exact terms (cell, tissue, organ, organ system).
Number the points to show the order.
Keep each point brief and to the point.
Avoid extra words like ‘for example’ or ‘such as’.

Common mistakes

Using ‘organism’ instead of ‘organ system’.
Mixing up the order of the levels.
Adding unnecessary details such as cell types or functions.

Mark scheme (4 marks)

Cell is the basic building block / simplest level of organisation
A tissue is a group of cells with a similar structure and function
Organs are aggregations of tissues performing specific functions
Organ systems are groups of organs that work together to form organisms

Key terms in this question

cell · organ