An ecologist estimates the number of cowslip plants in a wildflower strip in a botanical garden.
The strip has an area of 600 m2.
A quadrat with an area of 0.50 m2 is used at six positions in the strip. The six quadrats contain a total of 24 cowslip plants.
Two possible ways of choosing the positions are shown.
| Sampling plan | How positions are chosen |
|---|---|
| A | The ecologist chooses patches that look easy to reach. |
| B | A random number generator gives the coordinates for each position. |
Complete the partially worked calculation.
Mean number per quadrat =total number countednumber of quadrats=246=‾=\dfrac{\text{total number counted}}{\text{number of quadrats}}=\dfrac{24}{6}=\underline{\hspace{1.5cm}}=number of quadratstotal number counted=624= cowslip plants per quadrat.
Give one reason why the ecologist uses several quadrats rather than one quadrat.
Use the mean number per quadrat to calculate the population density of cowslip, in plants per m2\text{m}^2m2.
Use the population density to estimate the total number of cowslip plants in the strip.
Which sampling plan, A or B, should the ecologist use? Explain your choice.
109 exam-style questions on OCR GCSE Biology 6.1 Monitoring and maintaining the environment, covering 6.1.1 Field investigation of distribution and abundance, 6.1.2 Human interactions and biodiversity, 6.1.3 Maintaining biodiversity, and 6.1.4 Environmental change and distribution of organisms. Each one has a worked solution and a mark scheme showing where the marks go.