Question

In which one of the following free nuclear divisions occurs?
A. Flower formation
B. Endosperm formation
C. Gametes formation
D. Fruit formation

Answer 1

Hint: The division in which the cell wall after mitosis is not formed will be the answer. Mitosis generally is followed by cytokinesis which will divide the cell into two halves. Skipping this process will not form the cell wall between two cells and there will be free nuclei in the cytoplasm.

Complete answer:
What is a nuclear division? Division of nucleus in mitosis during cell division to give rise to two daughter cells is nuclear division. This occurs only once.
A free nuclear division is not followed by cytokinesis (which divides the cytoplasm into two daughter cells).

Let us see which of the options given follows the free nuclear division.
> Option A- Flower formation: Flowers are the reproductive part of a plant. They are produced normally by both mitosis and meiosis occurring. The gametes become haploid, the division of cytoplasm and nucleus occurs to pass them to the two daughter cells.

> Option B- Endosperm formation: In the formation of endosperm, repetitive free nuclear divisions take place. The endosperm is cellular, nuclear or helobial. But the free nuclear division is a feature of only nuclear and helobial endosperm.
- In nuclear endosperm, the primary endosperm mother cell divides and this is not followed by the cell wall formation. This occurs in 56% of the angiosperms. The free nuclei remain in the cytoplasm of the embryo.
- In the helobial endosperm, there is a formation of micropylar and a chalazal chamber. The nucleus in micropylar remains undivided whereas the chalazal nucleus is divided by free nuclear division. This occurs in 19% of the angiosperms.

> Option C- Gametes formation: Gametes are formed by meiosis which will make them haploid. There will be two mitotic divisions to give rise to two sperm cells needed for double fertilization.

> Option D- Fruit formation: Fruit is formed by the walls of the ovary. This happens after the embryo and flower are formed.

So our answer is option B: Endosperm formation.

Note: Endosperm is a triploid cell formed when the binucleate egg cell is fertilized by the pollen. It usually provides nourishment to the developing embryo throughout the period. But after the process of maturation has occurred, it will act as storage for proteins. The endosperm is edible in some cases.