On a rocky shore, limpets feed on seaweed and shore crabs feed on limpets. A chemical leaks into several rock pools.
Scientists record these results.
| Sampling time | Pollutant concentration / mg dm−3\mathrm{mg\,dm^{-3}}mgdm−3 | Mean seaweed cover (%) | Mean number of limpets per rock pool | Mean number of shore crabs per rock pool |
|---|---|---|---|---|
| Before the leak | 0.0 | 72 | 38 | 9 |
| 2 weeks after the leak | 1.5 | 49 | 30 | 9 |
| 4 weeks after the leak | 3.0 | 28 | 18 | 5 |
For one of the rock pools, the scientists kept two records.
Record 1: the number of limpets in the pool.
Record 2: the number of each species of organism in the pool, together with the pollutant concentration and the water temperature.
Explain which level of organisation each record describes.
A scientist claims that the pollutant was the only cause of all the changes shown in the table.
Evaluate this claim.
82 exam-style questions on Edexcel GCSE Biology 9.1 Ecosystems and interdependence, covering 9.1.1 Levels of organisation in ecosystems, 9.1.2 Abiotic and biotic factors, 9.1.3 Importance of interdependence, 9.1.4 Parasitism and mutualism, and 9.1.5 Determining number of organisms in an area. Each one has a worked solution and a mark scheme showing where the marks go.