Some plants have mutant seeds that cannot make abscisic acid…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Some plants have mutant seeds that cannot make abscisic acid. In a wet season the seeds of such a plant sprout while they are still inside the fruit, on the parent plant.
- Why does a normal seed not sprout inside its fruit?
- What do the mutant seeds lack that a normal seed has?
- If a normal dormant seed is sprayed with gibberellic acid, what is likely to happen, and why?
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.
Step 1. (a) A normal seed holds enough ABA to keep it dormant. ABA is high and GA is low, so the embryo does not grow.
Step 2. (b) The mutant seeds lack abscisic acid. There is nothing to hold them back, so the embryo grows in the wet fruit.
Step 3. (c) The seed will probably begin to germinate. GA raises the GA side of the balance and works against ABA, so the block is lifted.
Answer: (a) ABA keeps it dormant; (b) abscisic acid; (c) it is likely to germinate, since GA works against ABA.
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