Fiducia TogetherCells to organisms
Cells, tissues, organs, systems — the hierarchy and why it matters.
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.
What it is
Cells form tissues, tissues form organs, organs form organ systems, and systems form an organism.
Where it applies
GCSE biology and combined science.
How it works
Each level is a group of the level below working together. Specialisation increases up the hierarchy, and the reason multicellular organisms need transport and exchange systems is that most cells are no longer in contact with the outside.
How to use it in your work
Use the hierarchy to structure answers about any organ system.
For exchange surfaces, always give the three adaptations — large surface area, thin, good blood supply or ventilation — and say why each helps.
Where to get help
Your teacher and your board's specification and mark scheme.
Revise this with a song
These are ours. We write revision songs because a lot of people remember a tune when they cannot remember a page, and because revising out loud in the kitchen beats staring at a highlighter.
- The Biology Song The GCSE biology specification, set to music.
Where to read more
Last reviewed 2026-08-28 by Fiducia Together · Next review due 2027-08-28
Please note: This page explains a word or a process in education. It is general information about the system, the law and the guidance in England — not advice about your child, your school or your exam. If a decision is going against you, get advice from one of the free services we link to before you agree to anything or miss a deadline. If you are revising, check your own exam board's specification: boards word things differently and yours is the one that marks you.