Questions & Answers

Secondary nucleus formed by the fusion of two polar nuclei is also called
A. Vegetative nuclear
B. Generative nuclear
C. Primary endosperm
D. Definitive nucleus

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Hint: The polar nuclei are the two nuclei located in the center of the embryo sac. They fuse with the male nucleus, not the male who fuse with the egg. After fusion, the polar nucleus forms an endosperm, which serves as a food supply unit for dormant seeds.

Complete Answer:
The diploid nucleus formed by the fusion of two polar nuclei is called the secondary nucleus. It is also called the primitive endosperm nucleus.

The function of the secondary nucleus: It is the main food source for angiosperm embryos. Central cells are highly active cells that perform a variety of important functions in the embryo sac. The fusion of the secondary or polar nucleus and the sperm nucleus produces a primary endosperm nucleus, which is usually triploid.

The secondary nucleus formed by the fusion of two polar nuclei is also called definite nucleation. When microspores divide through mitosis to form a large vegetative cell and a small germ cell, there are vegetative nuclei and germ nuclei in the young pollen grains. The primary endosperm nucleus is formed by the fusion of the male gamete and the diploid secondary nucleus.

Thus, option D is the correct one.

Note: Angiosperms, any of the approximately 300,000 flowering plants, are the largest and most diverse group in the plant kingdom. Angiosperms are vascular seed plants in which the ovule (egg) is fertilized and develops into seeds in a closed hollow ovary.