Aquatic larvae need at least 4 mg/dm3 of dissolved oxygen. Scientists change the temperature in tanks containing equal numbers of larvae.
| Temperature | Oxygen concentration / mg/dm3\text{mg/dm}^3mg/dm3 | Larvae surviving / % |
|---|---|---|
| 15∘C15^\circ\text{C}15∘C | 8 | 90 |
| 25∘C25^\circ\text{C}25∘C | 3 | 20 |
| 25∘C25^\circ\text{C}25∘C | 8 | 85 |
Other conditions are controlled. Which conclusion best separates the effects of temperature and oxygen?
The large survival decrease at the higher temperature is mainly associated with oxygen shortage.
The large survival decrease at the higher temperature is mainly associated with heat alone.
The large survival decrease at the lower oxygen concentration is prevented by warmer water.
The large survival decrease at the lower oxygen concentration is prevented by cooler water alone.
40 exam-style questions on AQA GCSE Biology 7.1 Adaptations, interdependence and competition, covering 7.1.1 Communities, 7.1.2 Abiotic factors, 7.1.3 Biotic factors, and 7.1.4 Adaptations. Each one has a worked solution and a mark scheme showing where the marks go.