Name two substances that pass from the mother to the embryo through the placenta, and one that…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Name two substances that pass from the mother to the embryo through the placenta, and one that passes the other way. Why do the villi make the placenta good at this exchange?
Need a reminder? The key ideaShow
Fertilisation happens in the oviduct and gives a zygote, which divides (one cell, then 2, 4, 8, and so on) and settles in the thick lining of the uterus. The placenta passes glucose and oxygen to the embryo and removes its wastes. Without fertilisation the lining breaks down: menstruation, about once a month.
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. To the embryo. Glucose and oxygen.
Step 2. To the mother. The embryo's wastes, to be removed by the mother's body.
Step 3. The villi. Their finger-like shape gives a very large surface, so much can pass across at once.
Answer: glucose and oxygen go to the embryo, wastes come back; the villi give a large surface for exchange.
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