IGCSE Biology glossary
Quadrat
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 square frame (usually 0.25 m squared or 1 m squared) placed on the ground to sample the organisms within it. Quadrats are used with random sampling or along a transect to estimate population size and distribution of organisms in a habitat.
What to include in an exam answer
In practical paper questions, explain random sampling: use random number generators to choose coordinates, place the quadrat, count organisms inside. Repeat many times and calculate a mean. This avoids bias.
Example in context
Describe how to use quadrats to estimate the population of dandelions in a field (4 marks): Place quadrats at random positions using random number coordinates. Count the number of dandelions in each quadrat. Calculate the mean number per quadrat. Multiply by the total number of quadrats that would fit in the field to estimate the total population.
Related syllabus topic
Organisms & their environment