Researchers test how carbon dioxide concentration and water availability affect the establishment of seedlings. Each treatment starts with 100 seeds from the same plant species.
All other conditions are controlled, and the results are repeatable.
| Water availability | Carbon dioxide concentration / ppm | Number of established seedlings |
|---|---|---|
| Low | 400 | 20 |
| Low | 800 | 20 |
| High | 400 | 40 |
| High | 800 | 80 |
Which conclusion about possible changes in the species' distribution is best supported?
Increased carbon dioxide may improve establishment in wetter areas, but these results show no such improvement in drier areas.
Increased carbon dioxide may improve establishment in drier areas, but these results show no such improvement in wetter areas.
Increased carbon dioxide may improve establishment equally in both areas, because each area receives the same concentration increase.
Increased water may improve establishment equally at both concentrations, because each concentration receives the same water treatment.
40 exam-style questions on AQA GCSE Biology 7.2 Organisation of an ecosystem, covering 7.2.1 Levels of organisation, 7.2.2 How materials are cycled, 7.2.3 Decomposition, and 7.2.4 Impact of environmental change (HT only). Each one has a worked solution and a mark scheme showing where the marks go.