Which one of the following represents a correct form of mature angiosperm embryo sac?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 7 celled with 8 nuclei
Count the cells and the nuclei of the mature embryo sac:
Egg apparatus at the micropylar end: 2 synergids + 1 egg cell = 3 cells, 3 nuclei.
Antipodals at the chalazal end: 3 cells, 3 nuclei.
Central cell: 1 cell with 2 polar nuclei.
Total: 7 cells and 8 nuclei.
Option (1) 8 celled with 7 nuclei — Incorrect. The two numbers are reversed. A cell cannot be without a nucleus here, so there cannot be more cells than nuclei.
Option (2) 7 celled with 8 nuclei — Correct. The extra nucleus is the second polar nucleus sharing the central cell.
Option (3) 7 celled with 7 nuclei — Incorrect. It counts the central cell as having one nucleus. The central cell has two polar nuclei.
Option (4) 8 celled with 8 nuclei — Incorrect. It gives each of the eight nuclei its own cell. The two polar nuclei stay together in one central cell.
NCERT Extract:
The Pistil, Megasporangium (ovule) and Embryo Sac – …
