A tree nursery treated one batch of seeds with gibberellin and left another batch untreated.
The table shows the cumulative percentage of seeds that had germinated. No more seeds in either batch germinated after day 8.
| Time after sowing in days | Untreated seeds that had germinated in % | Gibberellin-treated seeds that had germinated in % |
|---|---|---|
| 4 | 20 | — |
| 8 | 75 | 80 |
On day 4, 39 of the 60 gibberellin-treated seeds had germinated.
Calculate how many percentage points greater the percentage germination was for the gibberellin-treated seeds than for the untreated seeds on day 4.
A worker claims that the main benefit of the gibberellin treatment is that the seeds germinate sooner, rather than that more seeds germinate overall.
Evaluate this claim using the data.
87 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.