A student tests five treatments on seeds of a wild plant…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student tests five treatments on seeds of a wild plant. Each treatment uses seeds. The table shows the per cent of seeds that germinated.
| Treatment | Seeds germinated (%) |
|---|---|
| None | 8 |
| Coat rubbed with sandpaper | 86 |
| Soaked in water for a day | 9 |
| Moist, in the cold for four weeks | 56 |
| Gibberellic acid | 72 |
- How many more seeds germinate with sandpaper than with no treatment?
- How many seeds stay dormant after the cold treatment?
- Soaking in water did almost nothing, but rubbing the coat worked well. What does this tell you about the cause of dormancy in this seed?
Need a reminder? The key ideaShow
A dormant seed is alive but does not germinate in good conditions. Causes: a hard coat, an immature embryo, inhibitors such as ABA, a need for cold or light. Cures: scarification, stratification, gibberellic acid, nitrate, light. ABA keeps a seed dormant and GA wakes it.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. seeds in each treatment.
Step 1. (a) The difference is per cent of seeds. That is seeds.
Step 2. (b) In the cold treatment per cent germinate, so per cent stay dormant: seeds.
Step 3. (c) Water washes out a soluble inhibitor, and it soaks a soft coat. It did nothing, so an inhibitor is not the main cause. Rubbing the coat worked, so the coat is the block. It is probably hard and does not let water enter.
Answer: seeds; seeds; the cause is a hard seed coat.
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