A tray containing young pea plants was accidentally left on its side. The growing regions of a shoot and a root were horizontal.
After four hours, a researcher recorded these results.
| Organ | Side | Relative auxin concentration | Mean increase in cell length in four hours / µm |
|---|---|---|---|
| shoot | upper | 2.1 | 18 |
| shoot | lower | 4.2 | 36 |
| root | upper | 2.0 | 30 |
| root | lower | 4.0 | 12 |
Using the results and your knowledge of auxin, explain the directions in which the shoot and the root will curve if the tray remains on its side.
105 exam-style questions on Edexcel GCSE Biology 6.3 Plant hormones, covering 6.3.1 Plant hormones and tropisms and 6.3.2 Commercial uses of plant hormones. Each one has a worked solution and a mark scheme showing where the marks go.