Question

Explain the formation of Embryo sac with the help of a diagram.

Hint:

The embryo sac is crucial for fertilization, as it houses the egg cell, which will fuse with the male gamete during fertilization.

Answer 1

Step 1: Overview of Embryo Sac Formation. - The embryo sac is formed in the ovule of a flower during the process of female gametogenesis. It is produced through a series of stages starting from the megaspore mother cell.
Step 2: Stages of Embryo Sac Formation. 1. Megaspore Mother Cell: The diploid megaspore mother cell undergoes meiosis to form four haploid megaspores. 2. Degeneration: Three of the four megaspores degenerate, leaving one functional megaspore. 3. Mitotic Divisions: The functional megaspore undergoes three successive mitotic divisions, resulting in eight nuclei. 4. Formation of Embryo Sac: These eight nuclei arrange themselves as follows: - One nucleus becomes the egg cell. - Two nuclei become the synergids. - One central nucleus becomes the central cell with two polar nuclei. - The remaining three nuclei become the antipodal cells.
Step 3: Diagram of Embryo Sac Formation.

Final Answer: The embryo sac is formed by meiosis and mitotic divisions of the megaspore mother cell, leading to the formation of eight haploid nuclei, which arrange into a mature embryo sac.