Final answer:
When pollen reaches a new flower, it travels down the pollen tube and fertilization occurs when the generative cell divides to form two sperm cells. One sperm cell fuses with the egg to form a diploid zygote, while the other sperm cell fuses with the polar nuclei to form the endosperm.
Step-by-step explanation:
When pollen reaches a new flower, it travels down the pollen tube, which forms to allow the pollen to migrate toward the female gametophyte. The fertilization process occurs when the generative cell, which is inside the pollen tube, divides to form two sperm cells. One sperm cell fuses with the egg to form a diploid zygote, while the other sperm cell fuses with the polar nuclei to form the endosperm.