Question 17
HA grower investigated the effect of the concentration of auxin in a rooting powder on the number of roots grown by cuttings. She used 20 cuttings at each concentration and kept all of the cuttings in the same conditions for three weeks. The figure shows her results.
Figure: The mean number of roots per cutting for cuttings treated with rooting powders containing six different concentrations of auxin
a.[1]
Use the figure. Give the concentration of auxin that produced the greatest mean number of roots per cutting.
b.[2]
Describe the effect on the cuttings of increasing the concentration of auxin above this value.
c.[1]
Suggest one reason why a very high concentration of auxin produces fewer roots.
d.[2]
The grower used 20 cuttings at each concentration. Explain why.
5.4 Plant hormones Questions
59 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.