Researchers germinated seeds in transparent nutrient gel kept in complete darkness. The roots and shoots were initially growing horizontally.
Angles above the horizontal were recorded as positive values. Angles below the horizontal were recorded as negative values.
| Time after germination in hours | Mean root angle in degrees | Mean shoot angle in degrees |
|---|---|---|
| 6 | −8 | +5 |
| 24 | −56 | +47 |
Calculate how many more degrees the roots turned through than the shoots between 6 hours and 24 hours.
Explain why the roots and shoots curved in opposite directions.
A change causes root cells to respond to a high auxin concentration in the same way as shoot cells.
If a seedling with this change germinated in soil, suggest how this would affect the direction of root growth and the seedling.
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.