Try it on paper first. A hint, the key idea and the worked solution are here when you need them.
A zygote divides into two cells, and every cell divides again at each step. How many divisions are needed before the embryo has more than cells, and how many cells does it then have?
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.
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. Double each time. .
Step 2. Count the divisions. That is divisions; is not yet above , but is.
Answer: divisions, giving cells.
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