A plant breeder needs 1200 pollen grains for a cross…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A plant breeder needs pollen grains for a cross. A sac of a flower has only pollen mother cells, and all of them complete meiosis.
- How many pollen mother cells are needed for grains?
- How many grains can the cells make?
- By how many grains is the sac short?
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. Need grains. Have PMCs.
Plan. One PMC makes four grains.
Step 1. Cells needed. PMCs.
Step 2. Grains made. grains.
Step 3. The shortfall. grains. This is PMCs short, since .
Answer: cells; grains; grains short.
Check. PMCs are missing, and grains.
Watch out. Dividing by two, as for gametes, would give the wrong number of PMCs.
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