Identify the correct sequence of formation of embryo sac or female gametophyte in flowering plants?
(A) Female gametophyte
(B) 2-nucleate embryo sac
(C) Megaspore mother cell
(D) 4-nucleate embryo sac
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (C), (B), (D), (A)
(C) Megaspore mother cell — first. This diploid cell in the ovule divides by meiosis into four megaspores; usually only one survives as the functional megaspore.
(B) 2-nucleate embryo sac — second. The nucleus of the functional megaspore divides by mitosis into two, and the two nuclei move to opposite poles.
(D) 4-nucleate embryo sac — third. A second mitotic division gives four nuclei.
(A) Female gametophyte — last. A third division gives 8 nuclei; cell walls form, and the mature 7-celled, 8-nucleate embryo sac is the female gametophyte.
NCERT Extract:
The Pistil, Megasporangium (ovule) and Embryo Sac – …
Figure 1.8 (a) Parts of the ovule showing a large megaspore mother cell, a dyad and a tetrad of megaspores; (b) 2, 4, and 8-nucleate stages of embryo sac and a mature embryo sac; (c) A diagrammatic representation of the mature embryo sac