Botany - Sexual Reproduction in Flowering Plants Question with Solution | TestHub
From the following, select the processes which take place during the development of embryo sac.
Functional megaspore divides by three mitotic divisions.
Type of nuclear division is free, where no cell wall formation takes place.
Among eight nuclei, six are surrounded by a cell wall.
Central cell is situated below the egg apparatus.
Options:
Answer:
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-nucleated and later the 8-nucleated stages of the embryo sac. It is interesting to note that these mitotic divisions are strictly free nuclear type. 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, is 8-nucleated and 7-celled.
