How many meiotic and mitotic divisions need to occur for the development of a mature female gametophyte from the megaspore mother cell in an angiosperm plant? (NEET 2025)

Solution & Explanation

Answer: A. The megaspore mother cell (MMC) divides meiotically (1 meiosis) to produce four megaspores. Only one functional megaspore survives and its nucleus undergoes three successive free-nuclear mitotic divisions — the first gives the 2-nucleate stage, and two more give the 4-nucleate and then 8-nucleate stages — which organise into the mature female gametophyte. Therefore 1 meiosis and 3 mitoses are required. NCERT: Ch 1, p.11, lines 5-9 — "The nucleus of the functional megaspore divides mitotically to form two nuclei which move to the opposite poles, forming the 2-nucleate embryo sac. Two more sequential mitotic nuclear divisions result in the formation of the 4-nucleate and later the 8-nucleate stages of the embryo sac." (preceded by p.9-10: MMC undergoes meiotic division producing four megaspores).