Identify the correct respective ploidy levels of the following structures in a typical mature, unfertilized angiosperm ovule: Nucellus, Antipodal cell, Secondary nucleus, and Synergid.

Step-by-step solution

The nucellus is the central mass of the ovule, representing the megasporangium, and is a diploid ( 2n ) sporophytic tissue. Antipodal cells are part of the female gametophyte (embryo sac) and are haploid ( n ). The secondary nucleus is formed by the fusion of two haploid polar nuclei in the central cell prior to fertilization, making it diploid ( 2n ). It is not triploid ( 3n ) until after triple fusion occurs. Synergids are also part of the female gametophyte and are haploid ( n ). Thus, the correct sequence of pl