Cambridge O Level Biology · Syllabus 5090 · Coordination and Response in Plants
Biological Variation
What is Biological Variation?
The natural differences between individual organisms of the same species, including differences in growth rate and in the size of a response. It is the reason several individuals are used in an investigation and a mean is calculated, since a single individual may not be representative.
This definition is part of the Coordination and Response in Plants chapter in Cambridge O Level Biology.
Common mistakes with Biological Variation
- 15. “One seedling is enough to show the response.” Why it is wrong: individuals of the same species differ in growth rate and in the size of their response, so a single seedling may be unrepresentative. SaySeveral seedlings are used and a mean calculated, so that biological variation does not determine the result.
Questions students ask about Biological Variation
Why are several seedlings used instead of one?
Because of biological variation: individuals of the same species grow at different rates and respond by different amounts, so one seedling may be unrepresentative. Using several allows a mean to be calculated and any anomalous individual to be identified.
Last reviewed Syllabus 2026-2028