1. Tardigrade
  2. Question
  3. Biology
  4. Which of the following statements are correct regarding the development of embryo sac? (i) The type of nuclear division is free, in which there is no formation of the cell wall. (ii) Out of the eight nuclei, six are surrounded by a cell wall. (iii) Central cell situated below the egg apparatus.

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. Which of the following statements are correct regarding the development of embryo sac?
(i) The type of nuclear division is free, in which there is no formation of the cell wall.
(ii) Out of the eight nuclei, six are surrounded by a cell wall.
(iii) Central cell situated below the egg apparatus.

NTA AbhyasNTA Abhyas 2020Sexual Reproduction in Flowering Plants

Solution:

The nucleus of the functional megaspore divides mitotically to form two nuclei which move to the opposite poles, forming the 2-nucleate embryo sac. Two more sequential mitotic nuclear divisions result in the formation of the 4-nucleate and later the 8-nucleate stages of the embryo sac. It is of interest to note that these mitotic divisions are strictly free nuclear. There is a characteristic distribution of the cells within the embryo sac. Three cells are grouped together at the micropylar end and constitute the egg apparatus. The egg apparatus, in turn, consists of two synergids and one egg cell. Three cells are at the chalazal end and are called the antipodals. The large central cell, as mentioned earlier, has two polar nuclei. Thus, a typical angiosperm embryo sac, at maturity, though 8-nucleate is 7-celled.