Practice question

Megasporogenesis occurs within ovule nucellus where subepidermal archesporial cell enlarges into megaspore mother cell undergoing meiosis I and II producing linear tetrad of four haploid megaspores with distinct animal-vegetal polarity. Three megaspores positioned toward micropyle undergo programmed cell death degenerating completely, while chalazal-most megaspore located near nutrient supply survives as functional megaspore. This selective survival establishes female germline lineage. Functional megaspore subsequently undergoes megagametogenesis involving three consecutive free nuclear mitoses without cytokinesis generating eight-nucleate embryo sac representing highly reduced female gametophyte generation.