You're so full of sh!t, it's amazing! An ovum is alive as a cell. Only God derives life from the lifeless. What a Maroon you're proving yourself to be ...
The "morning after pill" couldn't work faster than the zygote can divide.
I think the precise point used as a marker for successful fertilization is the expulsion of the polar body and the fusion of the nuclei of the sperm and oocyte. However, the *usual* marker in the real world would be division or replication of the chromosomes.
http://www.l4l.org/library/mythfact.html ""2) Fertilization
Now that we have looked at the formation of the mature haploid sex gametes, the next important process to consider is fertilization. O'Rahilly defines fertilization as:
"... the procession of events that begins when a spermatozoon makes contact with a secondary oocyte or its investments, and ends with the intermingling of maternal and paternal chromosomes at metaphase of the first mitotic division of the zygote. The zygote is characteristic of the last phase of fertilization and is identified by the first cleavage spindle. It is a unicellular embryo."9 (Emphasis added.)
The fusion of the sperm (with 23 chromosomes) and the oocyte (with 23 chromosomes) at fertilization results in a live human being, a single-cell human zygote, with 46 chromosomes — the number of chromosomes characteristic of an individual member of the human species. Quoting Moore:
"Zygote: This cell results from the union of an oocyte and a sperm. A zygote is the beginning of a new human being (i.e., an embryo). The expression fertilized ovum refers to a secondary oocyte that is impregnated by a sperm; when fertilization is complete, the oocyte becomes a zygote."10 (Emphasis added.)
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The oocyte is living - it's not an individual organism until it is somehow stimulated to replicate the chromosomes and the nucleus with the proper chromosomes begins mitosis. Then, she's an individual of that species as long as she lives.