Question

a) Explain the phenomenon of double fertilization.
b) Describe the post-zygotic events leading to implantation and placenta formation in humans. Mention any two functions of placenta.

Answer 1

After triple fusion, the central cell becomes the primary endosperm cell (PEC). The primary endosperm nucleus gives rise to the endosperm, while the zygote develops into embryo.
b) Function of Placenta: 1. Placenta secrets like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens and progestogens that are necessary to maintain pregnancy.
2) Umblical cord, the structure that connects the placenta with the foetus, is formed.