A researcher grew young bean seedlings on moist paper.
On each seedling, two lines were marked 5.0 mm apart on either the growing region of the shoot or the growing region of the root. A paste containing auxin at a concentration of 0 or 3 arbitrary units was applied to the tissue between the lines.
After 8 hours, the distance between the lines was measured.
| Plant organ | Auxin concentration in arbitrary units | Distance between lines after 8 hours in mm\text{mm}mm |
|---|---|---|
| shoot | 0 | 5.8 |
| shoot | 3 | 7.1 |
| root | 0 | 6.0 |
| root | 3 | 5.3 |
The increase in distance can be calculated using this equation.
increase in distance=final distance−starting distance\text{increase in distance} = \text{final distance} - \text{starting distance}increase in distance=final distance−starting distance
Calculate the increase in distance for the shoot treated with 3 arbitrary units of auxin.
Compare the effect of 3 arbitrary units of auxin on the growth of the shoot and the root.
Use data from the table in your answer.
Another shoot was kept upright in darkness. Auxin at a concentration of 3 arbitrary units was applied to the left side of its growing region. Auxin at a concentration of 0 arbitrary units was applied to the right side.
Explain which direction the shoot would curve.
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.