Question

Polygonam type of embryosac is a structure of -
(a) 8 nucleate and 7 celled (b) 7 nucleate and 8 celled
(c) 6 nucleate and 5 celled (d) 5 nucleate and 6 celled​

Answer 1

Answer:

follow

Explanation:

Polygonum type of embryo sac is the most common type of embryo sac found in plants. A diploid Megaspore mother cell is developed inside the nucellus. It then undergoes meiotic division to form four haploid megaspores. Out of these four megaspores, three degenerate and only one remains functional which take part in the formation of the embryo sac. Thus, it is monosporic. This functional megaspore then undergoes mitosis three times without cytoplasmic divisions which results in 8 nuclei in the megaspore. Three of these 8 nuclei get organized into egg apparatus (consisting of an egg cell and two synergids) at the micropylar pole, two nuclei form a large central cell and three nuclei get organized in antipodal cells at the chalazal pole. This results in the formation of a 7-celled but 8-nucleate structure which is called the embryo sac. Hence, the assertion is correct.

This type of embryo sac was first studied by Strasburger in Polygonum.

Hence reason is incorrect.

So, the correct answer is C.