Question

Synergids of the polygonum type embryo sac are

• A. Haploid
• B. Diploid
• C. Triploid
• D. Polyploid

Answer 1

Answer: (A)

Haploid

Polygonum-type embryo sac has one egg cell, two synergids, three antipodal cells, and a central cell that contains two nuclei. The diplod cell of the embryo sac forms the mother cell and undergoes meiosis to form four haploid cell. Out of four, three degenerates and one forms the female megaspore. The megaspore undergoes three successive mitotic division which leads to formation of four nuclei each at both the ends i.e., at the micropylar and the chalazal end in the embryo sac.

At the micropylar end, out of the four nuclei only three differentiate into two synergids and one egg cell. Together they are known as the egg apparatus. Synergid is haploid because it is formed by the meiosis of the nuclei at the micropylar end. Similarly, at the chalazal end, three out of four nuclei differentiates as antipodal cells. The remaining two cells (of the micropylar and the chalazal end) move towards the centre and are known as the polar nuclei, which are situated in a large central cell.

So, the correct answer is option A.