Question

In Polygonum type of embryo sac, the cells are

• A. Haploid
• B. Diploid
• C. Both A and B
• D. Polyploid

Answer 1

Answer: (C)

Both A and B

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. 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. The two polar nuclei get fused prior to fertilisation, resulting in the formation of a diploid secondary nucleus. This results in the formation of a 7-celled but 8-nucleate structure which is called the embryo sac. Hence, both haploid and diploid cells are present in the Polygonum type of embryo sac.

So, the correct answer is C.