# Describe the levels of organisation found in a multicellular organism, starting from the least complex level and ending with the most complex level.

> Pearson Edexcel International GCSE Biology (4BI1) — 2.1 Levels of organisation · Describe · 4 marks

> Multicellular organisms are made up of many different components that are arranged in a hierarchy from the simplest to the most complex.

## Mark scheme (4 marks)

1. Cell is the least complex / basic level of organisation; described as the basic building block of living organisms
2. Tissue is a group of cells with a similar structure and function
3. Organ is an aggregation of tissues performing a specific function
4. Organ system is the most complex level; groups of organs that work together to form / within organisms

## Key terms

- [cell](https://www.gradenine.co.uk/glossary/cell)
- [organ](https://www.gradenine.co.uk/glossary/organ)

## Related

- [Revision notes for Pearson Edexcel International GCSE Biology (4BI1)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/describe-the-levels-of-organisation-found-6d2bb7f0) · Published by Druglandscape Ltd.