In angiosperms the correct sequence of events in formation of female gametophyte in the ovule is : (A) 3 successive free nuclear divisions functional megaspore. (B) Degeneration of 3 megaspores. (C) Meiotic division in megaspore mother cell. (D) Migration of 3 nuclei towards each pole. (E) Formation of wall resulting in seven celled embryosac. Choose the correct answer from the options given below :

Sexual Reproduction in Flowering Plants PYQ — NEET 2023 · Q33 with Solution

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Correct answer: D

The process of female gametophyte formation in angiosperms, also known as megagametogenesis, involves several steps :

1. Meiotic division in the megaspore mother cell (megasporocyte) - This division leads to the production of four haploid cells, which are the megaspores.
2. Degeneration of three of the four megaspores - Typically, three of these megaspores degenerate, leaving a single functional megaspore.
3. Successive mitotic divisions (not meiotic) in the functional megaspore - These divisions are typically free-nuclear (the nuclear membrane does not break down between divisions), and result in a multinucleate cell.
4. Migration of the nuclei to the cell periphery and formation of cell walls - This results in the creation of a seven-celled structure known as an embryo sac or female gametophyte.
5. The final structure of the female gametophyte includes an egg apparatus (one egg cell and two synergids), two polar nuclei in the central cell, and three antipodal cells.

Given these steps, the correct sequence of events in the formation of the female gametophyte is :

Option D : (C), (B), (A), (D), (E)