A plant species needs moist soil.
A drainage channel is dug along one edge of a meadow. Ecologists investigate whether this environmental change affects the distribution of the plant.
Before the channel is dug and three years afterwards, the ecologists sample a total of 20 quadrats at each distance, four on each of five transects. The distances are measured from the line where the channel is dug. The same transects and quadrat size are used in both surveys.
| Distance from the drainage channel in m | Quadrats containing the plant before drainage | Mean soil water content three years after drainage in % | Quadrats containing the plant three years after drainage |
|---|---|---|---|
| 5 | 16 | 18 | 3 |
| 15 | 15 | 24 | 8 |
| 30 | 16 | 31 | 13 |
| 50 | 15 | 37 | 16 |
Evaluate the conclusion that the drainage channel changed the distribution of the plant. Predict how the distribution would change if the channel were blocked and the meadow became wetter.
83 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.