Summary
The levels of organisation in biology describe the hierarchy of complex biological structures and systems that define life using a reductionistic approach.
- Cell — the basic structural and functional unit of life Example: Red blood cell
- Tissue — a group of similar cells that perform a specific function Example: Muscle tissue
- Organ — a structure made up of different tissues working together Example: Heart
- Organ System — a group of organs that work together to perform complex functions Example: Digestive system
- Organism — an individual living entity Example: Human
Exam Tips
Key Definitions to Remember
- Cell: the basic structural and functional unit of life
- Tissue: a group of similar cells that perform a specific function
- Organ: a structure made up of different tissues working together
- Organ System: a group of organs that work together to perform complex functions
- Organism: an individual living entity
Common Confusions
- Confusing tissues with organs
- Misunderstanding the difference between an organ and an organ system
Typical Exam Questions
- What is the basic unit of life? Cell
- How do tissues differ from organs? Tissues are groups of similar cells, while organs are made of different tissues.
- Give an example of an organ system. Digestive system
What Examiners Usually Test
- Understanding of the hierarchy from cells to organisms
- Ability to provide examples of each level of organisation