Scientists cut the tips off two shoots and placed each tip on two agar blocks separated by a thin sheet of mica. Auxin cannot pass through mica. Auxin moved from each half of the tip into the agar block below it.
After three hours, the scientists measured the amount of auxin in each agar block.
The Table shows the results.
Table
| Tip | Auxin in block under side A in arbitrary units | Auxin in block under side B in arbitrary units |
|---|---|---|
| 1 (dark) | 25 | 25 |
| 2 (light from side A) | 17 | 33 |
Calculate the percentage of the total auxin from tip 2 that was collected in the block under side B.
Explain what the results show about the effect of light on auxin in the tip.
The two agar blocks from tip 2 were each placed centrally on the cut top of a different shoot that had had its tip removed. The shoots were kept in the dark.
Predict which shoot grew taller and explain your answer.
Explain why the shoots in part (c) were kept in the dark.
46 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.