A fruit grower applies four sprays to equal groups of flower clusters on grapevines of the same variety. The volume of spray and all other growing conditions are the same. The grower records the mean mass of the ripe grapes.
| Spray applied | Mean mass of a ripe grape (g) |
|---|---|
| Water | 4.2 |
| Carrier solution P only | 4.4 |
| Carrier solution P with gibberellin | 6.8 |
| Carrier solution Q with gibberellin | 7.1 |
One proposed comparison changes both the gibberellin treatment and the carrier solution, so it cannot show which change caused the difference in mean mass. Which pair of results has this problem?
compare 7.1 g with 6.8 g
compare 7.1 g with 4.4 g
compare 6.8 g with 4.4 g
compare 4.4 g with 4.2 g
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.