IGCSE Biology glossary
Species
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 group of organisms that can reproduce to produce fertile offspring.
What to include in an exam answer
the key term is 'fertile'. Saying organisms simply 'can breed' or 'produce offspring' drops the mark, because different species (like a horse and a donkey) can produce offspring, but a mule is sterile. This definition underpins the binomial system and classification questions in Paper 4.
Example in context
Asked why a mule is not evidence that horses and donkeys are one species: 'A mule is sterile, and members of the same species must reproduce to produce fertile offspring.'
Related syllabus topic
Characteristics & classification of living organisms