Outline7 marksChallenge
A student investigated the effect of auxin (IAA) on cell elongation in oat coleoptile segments. Segments were placed in buffer solutions with different IAA concentrations. After 2 hours, the length of the segments and the pH of the surrounding solution were measured. The results are shown in the table.
| IAA concentration (ppm) | Mean segment length (mm) | pH of solution |
|---|---|---|
| 0 | 5.0 | 6.5 |
| 10 | 6.2 | 5.8 |
| 100 | 7.5 | 5.2 |
(a) Outline the mechanism by which auxin brings about cell elongation.
(b) Outline how the rapid closure of the Venus fly trap is achieved when the sensitive hairs on the leaf lobes are stimulated.
(c) Outline the role of gibberellin in the germination of barley seeds.