A native water snail species lives only in one freshwater spring. The snail feeds on algae growing on stones.
Immediately after the first survey, a different water snail species that also feeds on the algae was introduced into the spring.
Scientists estimated the snail populations and the percentage of the stones covered by algae.
| Years after the first survey | Introduced snails | Stones covered by algae (%) | Native adult snails | Native young snails |
|---|---|---|---|---|
| 0 | 0 | 68 | 620 | 240 |
| 3 | 85 | 51 | 480 | 130 |
| 6 | 270 | 30 | 270 | 45 |
| 9 | 510 | 14 | 110 | 6 |
Evaluate the claim that the native snail species is unlikely to become extinct because 110 adults were still alive in year 9.
Use the data in your answer.
71 exam-style questions on AQA GCSE Biology 6.3 The development of understanding of genetics and evolution, covering 6.3.1 Theory of evolution, 6.3.2 Speciation, 6.3.3 The understanding of genetics, 6.3.4 Evidence for evolution, 6.3.5 Fossils, 6.3.6 Extinction, and 6.3.7 Resistant bacteria. Each one has a worked solution and a mark scheme showing where the marks go.