Observe the given diagram and answer the questions given below:

How many mitotic divisions occur in the nucleus of the functional megaspore to form embryo sac?

Three

The correct answer is Option (4) – Three

The embryo sac, also known as the female gametophyte, is a crucial structure within the ovule of a flowering plant. It is formed through the process of megasporogenesis, which involves the differentiation and development of a single megaspore mother cell within the ovule. The megaspore mother cell undergoes meiosis to produce four haploid megaspores. Out of these four megaspores, three degenerate and only one megaspore survives and develops into the embryo sac.

The surviving megaspore undergoes three rounds of mitotic divisions without cytokinesis, resulting in the formation of eight haploid nuclei. These nuclei become organized into different cells within the embryo sac through the formation of cell walls. The organization of the nuclei and cells within the embryo sac varies among different species, but a common pattern consists of three antipodal cells at the chalazal end, two synergid cells and egg cell near the micropyle, a centrally located large central cell containing two polar nuclei.