Ecologists capture, harmlessly mark and release 84 grasshoppers in an area of rough grassland. After the marked grasshoppers have mixed back into the population, they capture a second sample of 70 grasshoppers. Of these, 14 are marked.
The estimated population size is calculated using:
N=n1×n2m2N=\dfrac{n_1\times n_2}{m_2}N=m2n1×n2
N N\,N is the estimated population size, n1 n_1\,n1 is the number initially caught and marked, n2 n_2\,n2 is the total number in the second sample, and m2 m_2\,m2 is the number of marked individuals in the second sample.
Calculate the estimated number of grasshoppers in the area of rough grassland.
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.