A scientist investigated how the same uneven distribution of auxin affects an intact shoot and an intact root. Both organs were initially vertical and were kept in darkness throughout the investigation, with their growing regions free to curve.
In each organ, the scientist maintained a higher auxin concentration on side P than on side Q of the growing region.
The mean cell length on each side was measured at the start and after 8 hours.
| Organ | Side | Mean cell length at start in μm\mu\text{m}μm | Mean cell length after 8 hours in μm\mu\text{m}μm |
|---|---|---|---|
| shoot | P | 40 | 64 |
| shoot | Q | 40 | 48 |
| root | P | 20 | 22 |
| root | Q | 20 | 30 |
Calculate the ratio of the percentage increase in mean cell length on side P of the shoot to the percentage increase in mean cell length on side P of the root.
Explain the direction in which the shoot and the root would be expected to curve after 8 hours.
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.