IGCSE Biology glossary
Discontinuous variation
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
Variation that falls into distinct, separate categories with no intermediates. Examples include blood group (A, B, AB, O), tongue rolling (can or cannot) and eye colour. Discontinuous variation is usually controlled by a single gene and is not influenced by the environment.
What to include in an exam answer
Discontinuous variation is displayed as a bar chart (not a histogram). The categories are distinct. Examples: blood group, sex, ability to roll the tongue.
Example in context
State one example of discontinuous variation and explain why it is discontinuous (2 marks): Blood group (A, B, AB or O) is discontinuous because individuals fall into distinct categories with no intermediate types between them.
Related syllabus topic
Variation & selection