(a) (i) Explain the process of double fertilization in an angiosperm starting from the germination of pollen grains on the stigma, mentioning the ploidy of the end products formed at the end. State the role of synergids during the course of the process.
(ii) Why does the development of endosperm precede that of the embryo?
OR
(b) (i) Mention the site where fertilization of the ovum occurs in a human female. Explain the process of fertilization and mention how polyspermy is prevented.
(ii) Name the embryonic stage that gets implanted in the uterus. Explain the process of implantation in a human female.