Estimating population size
AQA GCSE Biology calculation · part of the free Calculation Climb
Two exam methods. Quadrats: mean per quadrat × how many quadrat-areas fit in the whole area. Capture–recapture: population ≈ (1st sample × 2nd sample) ÷ number marked in the 2nd catch.
How to do it — step by step
- Quadrats: mean per m² × total area.
- Capture–recapture: (1st sample × 2nd sample) ÷ marked-and-recaught.
Worked example
5 daisies per 1 m² quadrat, field is 200 m².
estimate = 5 × 200 = 1000 daisies
Now practise it — free
Science Street's Calculation Climb walks you from a worked example, through a guided step-by-step version, to questions you do yourself — with fresh examples every time and a built-in calculator and periodic table. No sign-up needed.
Practise Estimating population size on Science Street →