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GCSE Biology · key term
A method of estimating the number of mobile organisms by marking a first sample and checking how many marked individuals appear in a second sample.
Used by OCR
Specification B6.1a · Paper 2 (Foundation), Paper 4 (Higher)
Revise: Field investigationFor these, capture–recapture can estimate population size. Catch a first sample of one species, count it, mark the animals harmlessly and release them where they were caught. Allow them to mix with the population, then catch a second sample in the same area.
Capture–recapture gives an estimate only if marks remain visible, marked organisms mix back into the population and marking does not change their chance of being caught.
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