Here's a breakdown:
* Embryo sac: This is the female gametophyte within the ovule of a flowering plant. It contains the egg cell (female gamete).
* Fertilization: This occurs when a pollen grain (containing the male gamete) lands on the stigma of a flower and grows a pollen tube down to the ovary, where the male gamete fuses with the egg cell.
* Zygote: The resulting cell from this fusion is the zygote, which is the first cell of the new sporophyte generation (the plant itself).
The zygote then undergoes mitosis and cell division, eventually developing into the embryo within the seed.
