AP BIOLOGY

Detailed explanation-1: -Eight celled. Hint: The embryo sac is the gametophyte of the angiosperm. The eight nuclei of the embryo sac are not separated by proper cell walls. During sexual reproduction, only one of the eight nuclei serves as the egg.

Detailed explanation-2: -gametophyte of angiosperms (called the embryo sac) is tiny and contains only a few (typically eight) nuclei; the cytoplasm associated more or less directly with these nuclei is not partitioned by cell walls.

Detailed explanation-3: -A mature embryo sac consists of two synergids, one egg cell and three antipodal cells with one nucleus each. Then there is one large central cell that has two nuclei. Hence, a mature embryo sac consists of 7 cells and 8 nuclei.

Detailed explanation-4: -Three cells present at the chalazal end of embryo sac are called as antipodals. The large central cell has two polar nuclei. This makes embryo sac 7 celled and 8 nucleate structure.

Detailed explanation-5: -Thus, a typical angiosperm embryo sac at maturity is 7-celled but 8-nucleated as the central cell has 2-nuclei.