IGCSE Biology glossary
Organism
Biology editorial review is supported by the named review panel. Reviewer participation may vary by guide. Checked against Cambridge IGCSE Biology 0610 (2026–2028); last reviewed August 2026.
Definition
A living thing that carries out all seven life processes: movement, respiration, sensitivity, growth, reproduction, excretion and nutrition (MRS GREN). Organisms can be unicellular (single-celled) or multicellular.
What to include in an exam answer
Being able to list and explain the seven characteristics of living things is a common early-paper question. Use the mnemonic MRS GREN to recall them.
Example in context
A student observes a specimen and is unsure if it is alive. State three life processes the student could test for (3 marks): Respiration (using oxygen or producing carbon dioxide), sensitivity (responding to stimuli), and growth (increase in size).
Related syllabus topic
Characteristics & classification of living organisms