A microsporangium has 50 pollen mother cells…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A microsporangium has pollen mother cells. All of them complete meiosis, and the plant sheds three-celled pollen. Count each pollen mother cell as one meiosis. Count each division of a nucleus by mitosis as one mitosis.
- How many meioses take place?
- How many pollen grains are formed?
- How many mitoses take place in all, from the microspores to the male gametes?
Need a reminder? The key ideaShow
A pollen mother cell (PMC) is diploid, with chromosomes. It divides by meiosis into four haploid microspores, with chromosomes each. Each microspore divides by mitosis into a vegetative cell and a generative cell. The generative cell divides by mitosis into two male gametes. Mitosis keeps the chromosome number.
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. PMCs and three-celled pollen.
Plan. Count the grains, then two mitoses for each grain.
Step 1. Meioses. One in each PMC, so .
Step 2. Grains. .
Step 3. Mitoses. In each grain, the microspore divides once and the generative cell divides once. That is mitoses.
Answer: ; ; .
Check. There are male gametes for each grain, so male gametes. Each mitosis added one cell.
Watch out. Do not count the meioses with the mitoses.
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