DENDROLOGY

Detailed explanation-1: -Double fertilization is a complex process where out of two sperm cells, one fuses with the egg cell and the other fuses with two polar nuclei which result in a diploid (2n) zygote and a triploid (3n) primary endosperm nucleus (PEN) respectively.

Detailed explanation-2: -Hence, the total number of nuclei involved in double fertilisation are five.

Detailed explanation-3: -After fertilization egg cell transforms into embryos, antipodal and synergid cells gets degenerated. And polar nuclei give rise to the triploid endosperm. Outer integuments get converted to testa, while inner integuments are transformed to tegmen.

Detailed explanation-4: -Double fertilization is a process of fertilization characterized by the fusion of a female gametophyte with two male gametes. In this mechanism, one sperm cell fuses with the egg-producing zygote, and the other fuses with the two polar nuclei to make the endosperm.