Young roots were held vertically in darkness. Equal-sized gel blocks containing auxin were placed against both sides of the zone just behind each root tip.
A 5.0 mm section of each root was marked. The table shows the mean length of the marked sections after 6 hours.
| Mass of auxin in each gel block in ng | Length at start in mm | Mean length after 6 hours in mm |
|---|---|---|
| 0 | 5.0 | 7.4 |
| 4 | 5.0 | 6.8 |
| 8 | 5.0 | 5.8 |
Calculate the ratio of the increase in length with 0 ng of auxin to the increase in length with 8 ng of auxin.
Use the results and your knowledge of auxin to explain the effect of auxin on the growth of the root sections.
Another root had a gel block containing 0 ng of auxin placed against its left side and a gel block containing 8 ng of auxin placed against its right side.
Suggest which direction this root would bend. Explain your answer.
87 exam-style questions on AQA GCSE Biology 5.4 Plant hormones, covering 5.4.1 Control and coordination and 5.4.2 Use of plant hormones (HT only). Each one has a worked solution and a mark scheme showing where the marks go.