Living Thing
A living thing carries out all seven life processes, each defined explicitly by the IGCSE syllabus — so the set doubles as a checklist for deciding whether something is alive 1:
| Process | IGCSE definition |
|---|---|
| Movement | An action by an organism or part of an organism causing a change of position or place |
| Respiration | Chemical reactions in cells that break down nutrient molecules and release energy for metabolism |
| Sensitivity | The ability to detect and respond to changes in the internal or external environment |
| Growth | A permanent increase in size and dry mass |
| Reproduction | The processes that make more of the same kind of organism |
| Excretion | Removal of the waste products of metabolism and substances in excess of requirements |
| Nutrition | The taking in of materials for energy, growth and development |
Remember them as MRS GREN: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.
Non-living and Borderline
A salt crystal grows and a candle flame moves and releases energy, but neither respires, excretes or is built of cells. Viruses (protein coat plus genetic material) reproduce only inside a host cell, so they are not fully living 1.
Related
- Organism - Individual living thing.
- Movement - Change of position or place.
- Respiration - Energy release in cells.
- Sensitivity - Response to change.
- Growth - Permanent increase in size and dry mass.
- Reproduction - More of the same kind.
- Excretion - Removal of waste.
- Nutrition - Materials for energy and growth.
- Biology - Cambridge IGCSE life-science area.
Footnotes
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Cambridge IGCSE Biology 0610 syllabus for examination in 2026, 2027 and 2028 - Characteristics of living organisms (1.1); viruses (1.3). ↩ ↩2