IGCSE Biology glossary
Dichotomous key
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 branching identification tool that presents a series of paired statements or questions, each with two choices. At each step the user selects the statement that matches the organism, eventually arriving at the correct identification.
What to include in an exam answer
In Paper 6 (practical), you may need to construct or use a dichotomous key. Each pair of statements must be observable, contrasting and lead to either another pair or a named organism.
Example in context
Construct a simple dichotomous key for four organisms (example step): 1a. Has wings... Go to 2. 1b. Does not have wings... Organism D.
Related syllabus topic
Characteristics & classification of living organisms