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13
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Your answer is A. 13 Hope this helps!
If the sperm cell fertilises the ovum, and implantation does not occur, then the corpus luteum degenerates and it turns into corpus albicans, stopping progesterone secretion. If fertilisation occurs and implantation also, the syncytiotrophoblast, the "root part" of the blastocyst (one of the early structures originated from the zygote), produces a hormone that is called <span>human chorionic gonadotropin (hCG). The hCG is what makes the corpus luteum keep secreting progesterone and maintain itself. The progesterone will then help keep the endometrium and, therefore, allow the development of the embryo to happen.</span>
Plant cells have chloroplasts. They also have cell walls. They are also rectangular. Animal cells are more round and they do not have chloroplasts or cell walls.Animal cells also have small vacuoles.While plant cells have a one large vacuole.
Passive diffusion is a form of passive transport and a type of diffusion by which particles from a high concentration gradient passes through a biological membrane to a low concentration gradient. Diffusion, or simple diffusion on the other hand, is the passage of molecules without the need of a membrane.
The cell grows and develop and the chromosomes duplicate. Also, interphase is the phase where the cell spends most of its time in.