Levels of organisation within organisms, smallest to largest
- Organelles – Highly organises structure (or rather, part) of a molecule that performs a specific function within their cell. For example, mitochondria, which stores energy for the human body’s cells
- Cells – Functional unit made up of organelles, eg. skin cells
- Tissues – A collection of similar cells that all serve a common function, eg the glandular tissue which produces enzymes and hormones
- Organs – made up of several kinds of tissues that act together to function as a unit, for example the heart, kidneys…
- Organ systems – Several organs grouped together to form a function, eg. the Respiratory system composed of the heart and lungs.