How does the nucleus of the functional megaspore divide to form the embryo sac?

Mitotically

The answer is b) Mitotically.

The nucleus of the functional megaspore divides mitotically to form the embryo sac. Meiosis is a type of cell division that reduces the number of chromosomes in a cell by half. In flowering plants, meiosis occurs in the megaspore mother cell to produce four haploid megaspores. However, only one of these megaspores is functional and develops into the embryo sac.

The functional megaspore then undergoes three rounds of mitosis to form the mature embryo sac. Mitosis is a type of cell division that produces two daughter cells that are genetically identical to the parent cell. In the case of the embryo sac, the three rounds of mitosis produce a cell with seven cells and eight nuclei. The egg cell, which is fertilized by a sperm cell to produce a zygote, is located in the micropylar end of the embryo sac.

The cells of the embryo sac are:

• Two synergids: These cells are located near the micropyle of the embryo sac and help to guide the sperm cells to the egg cell.
• An egg cell: This is the female gamete that can be fertilized by a sperm cell to produce a zygote.
• Three antipodals: These cells are located at the opposite end of the embryo sac from the egg cell and do not play a direct role in fertilization.
• One central cell

Asexually, and budding, are all types of cell division that can produce new cells. However, only mitosis is involved in the formation of the embryo sac from the nucleus of the functional megaspore.