MediumBiologyHigh School (11–12)Diversity of Living Organisms › Gymnosperms and AngiospermsNumerical
A plant has 14 chromosomes in each leaf cell.
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 has chromosomes in each leaf cell. One of its pods holds seeds. Give the number of chromosomes in its egg, in the zygote and in the primary endosperm nucleus. How many pollen tubes and how many male gametes were needed for the whole pod?
Need a reminder? The key ideaShow
In angiosperms, ovules lie inside an ovary. The embryo sac has 7 cells and 8 nuclei: the egg, 2 synergids, 3 antipodals and the central cell with 2 polar nuclei. One pollen tube brings two male gametes. Syngamy (gamete and egg) gives the zygote, . Triple fusion (gamete and two polar nuclei) gives the primary endosperm nucleus, .
The worked solution
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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. One set. , so . The egg has chromosomes.
Step 2. The zygote. Egg and male gamete: .
Step 3. The endosperm nucleus. Two polar nuclei and a male gamete: .
Step 4. The pod. seeds need pollen tubes and male gametes.
Answer: egg , zygote , primary endosperm nucleus ; pollen tubes and male gametes.
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