Put these events in the right order, and say where each happens in the body…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Put these events in the right order, and say where each happens in the body.
- The blastocyst is embedded in the endometrium.
- The secondary oocyte is released from the ovary.
- A zygote with chromosomes is formed.
- The morula forms a hollow cavity and becomes a blastocyst.
- The zygote divides into , and cells.
- Meiosis II is completed and the second polar body forms.
Need a reminder? The key ideaShow
Fertilisation takes place in the ampulla and gives a zygote with chromosomes. Cleavage gives cells after divisions, with no growth of the embryo. The morula has to cells. The blastocyst has a trophoblast and an inner cell mass. The ovum always carries X, and a sperm carries X or Y with equal chance. The trophoblast attaches to the endometrium in implantation.
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.
Step 1. (b) Ovulation, at the surface of the ovary.
Step 2. (f) A sperm enters, meiosis II is completed and the second polar body forms, in the ampulla.
Step 3. (c) The nuclei fuse and the zygote forms, in the ampulla.
Step 4. (e) The first cleavage divisions, as the embryo moves along the isthmus.
Step 5. (d) The morula forms the blastocyst, in the uterus.
Step 6. (a) Implantation, in the endometrium.
Answer: b, f, c, e, d, a.
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