Context
An ecological researcher investigated the relationship between water availability in soil and the physical development of root systems in arid-zone vegetation. She set out to determine whether there is a correlation between the average soil moisture content and the maximum root depth of mature Prosopis shrubs.
The researcher selected 15 distinct sampling sites across a semi-arid nature reserve. At each site, she measured the average soil moisture content (%) in the top 50 cm of soil over a growing season. She also carefully excavated and measured the maximum vertical root penetration depth (in cm) of a randomly selected mature Prosopis shrub at each site.
The findings from her measurements are shown in the table and the scatter diagram below.
Figure 1
Figure 1: Scattergram of average soil moisture content (%) and maximum root depth (cm) for 15 mature Prosopis shrubs
| Average soil moisture content (%) | Maximum root depth (cm) |
|---|---|
| 1.8 | 278 |
| 3.8 | 246 |
| 5.8 | 220 |
| 7.8 | 195 |
| 9.8 | 176 |
| 12.0 | 151 |
| 13.9 | 131 |
| 15.9 | 111 |
| 18.0 | 92 |
| 20.0 | 76 |
| 22.0 | 61 |
| 24.1 | 47 |
| 26.2 | 31 |
| 28.2 | 21 |
| 30.1 | 11 |
Using the data in Figure 1, outline the relationship between the average soil moisture content and the maximum root depth.
Correlations Questions
Practise AQA A Level Psychology Correlations with exam-style questions for A Level Psychology. 30 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.