Organism
An organism is an individual living thing: either a single cell or a multicellular body whose cells are organised into tissues, organs and organ systems that work together 1.
Levels of Organisation
| Level | Meaning | Example |
|---|---|---|
| Cell | Basic structural and functional unit | Palisade mesophyll cell |
| Tissue | Group of similar cells with one function | Palisade mesophyll tissue |
| Organ | Several tissues working together | Leaf |
| Organ system | Organs cooperating on a major function | Transport system |
| Organism | Whole, independently living individual | A flowering plant |
Unicellular organisms (Amoeba, bacteria) perform every life process in one cell; multicellular organisms divide labour between specialised cells — ciliated cells, neurones, gametes 1.
Classification
Organisms are grouped into five kingdoms — animal, plant, fungus, prokaryote, protoctist — and named by the binomial system of genus and species 1. A species is a group of organisms that can reproduce to produce fertile offspring.
Related
- Living Thing - Entity carrying out all seven life processes.
- Cell - Basic structural and functional unit.
- Movement - Change of position or place.
- Respiration - Release of energy in cells.
- Sensitivity - Detection of and response to change.
- Growth - Permanent increase in size and dry mass.
- Reproduction - Production of more of the same kind of organism.
- Excretion - Removal of metabolic waste and excess substances.
- Nutrition - Intake of materials for energy, growth and development.
- Biology - Cambridge IGCSE life-science area.
Footnotes
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Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028 - Levels of organisation (2.1), specialised cells (2.1.6), characteristics of living organisms (1.1), classification (1.2-1.3). ↩ ↩2 ↩3