Question

In angiosperm, triple fusion produces
 (A) Polar nucleus
(B) Secondary nucleus
(C) Primary endosperm nucleus
(D) Zygotic nucleus

Answer 1

Hint: The triple fusion takes place in an angiosperm which helps in the production of the triploid nucleus and the cell which helps in providing nourishment to the developing embryo. It is present inside the seed of most flowering plants.

Complete answer:
In Triple fusion, fusion takes place between two polar nuclei and the sperm nucleus. This triple fusion occurs due to double fertilization in seed plants and produces a triploid nucleus which is also known as the primary endosperm nucleus (PEN) .
This fusion takes place in an angiosperm which is a sexually reproducing plant. The primary endosperm nucleus further evolves into an endosperm. Endosperm has reserve food materials and is used to provide nutrition to the embryo. There are three types of endosperm development. They are:
- Nuclear endosperm formation - - In this repeated free- nuclear divisions take place. This type of endosperm is usually liquid. For example, Coconut water is an example of a nuclear endosperm.
- Cellular endosperm formation - -  In this, a cell- wall formation is coincident with nuclear divisions. Coconut meat is cellular endosperm.
- Helobial endosperm formation – In this type, a cell wall is found between the first two nuclei, so because of which one half develops endosperm along with the cellular pattern, and the other half along with the nuclear pattern i.e endosperm is divided with both the patterns.
So, the correct answer is ‘(C) Primary endosperm nucleus’.

Note: Double fertilization, the name clearly suggests that the fertilization is taking place twice. After pollination, the pollen tube releases two sperm cells. One of the sperm nuclei fertilizes the egg cell, forming a zygote, while the other sperm nuclei usually fuse with the central cell, forming a primary endosperm cell.