People used vaccines to reduce the risk of infection by working with body as defenses to help them so this vaccines develop immunity to disease
I hope that's help:0
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>
The answer is 4 chemical energy from the grass.
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