Final answer:
During angiosperm germination, double fertilization occurs where one sperm fertilizes the egg to form a diploid zygote that becomes the embryo, while the other sperm creates a triploid cell that develops into the endosperm, providing food for the embryo.
Step-by-step explanation:
In angiosperms, a unique process known as double fertilization occurs following the deposition of pollen on the stigma and the germination of the pollen tube.
When the pollen tube reaches the female gametophyte in the ovule, the generative cell that traveled through the pollen tube divides into two sperm cells. One sperm cell combines with the egg to form a diploid zygote, which eventually develops into the embryo of a seed plant.
The other sperm cell fuses with the central cell, which contains two polar nuclei, resulting in a triploid cell. This cell will develop into the endosperm, which provides a food reserve for the developing embryo.
The zygote turns into an embryo with a radicle and cotyledons, which facilitate the transfer of nutrients from the endosperm to the growing embryo. The entire process is integral to the formation of the seed, which later germinates into a new plant.