A flower of the pea plant gives a pod with 7 ovules…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A flower of the pea plant gives a pod with ovules. Each ovule had one MMC, and every MMC completed meiosis. One megaspore in each ovule was functional.
- How many MMCs were there?
- How many megaspores were formed in all?
- How many megaspores degenerated?
Need a reminder? The key ideaShow
An ovule has one megaspore mother cell (MMC), which is diploid. The MMC divides by meiosis into four haploid megaspores. In most plants, one is functional and three degenerate. The functional megaspore divides by mitosis three times, with no walls, to make 8 nuclei. The mature embryo sac has 7 cells: the egg, 2 synergids, 3 antipodals and the central cell with 2 polar nuclei.
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. ovules, one MMC in each. One functional megaspore in each ovule.
Plan. Count the megaspores from the MMCs. Take away the functional ones.
Step 1. The MMCs. One in each ovule, so .
Step 2. The megaspores. .
Step 3. The degenerate ones. , which is .
Answer: ; ; .
Check. Seven functional megaspores make seven embryo sacs, one for each ovule.
Watch out. The numbers are for the ovules. The pod is not one MMC.
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