Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a teaching model, the viability of a sample of pollen halves every minutes after the pollen is released. At the start, of the pollen is viable.
A pollen grain is the male gametophyte. Its exine is made of sporopollenin and has germ pores. Its intine is made of cellulose and pectin. A grain is about to micrometres wide, and mm is micrometres.
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. Half-life minutes. Start: .
Plan. Halve the viability once for each half-life.
Step 1. After 20 minutes. Two half-lives: , so .
Step 2. After 30 minutes. Three half-lives: , so .
Step 3. The time for 12.5 per cent. It is reached after three half-lives, which is minutes.
Answer: ; ; minutes.
Check. .
Watch out. This is a model. Real pollen of rice and wheat stays viable for about minutes in all.
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