Question

Which is the correct order for the development of embryo sac?

• A. Megaspore $\to$ Megaspore mother cell $\to$ Embryo sac
• B. Megaspore $\to$ Embryo sac $\to$ Megasporangium
• C. Megaspore mother cell $\to$ Embryo sac $\to$ Megaspore
• D. Megaspore mother cell $\to$ Megaspore $\to$ Embryo sac

Answer 1

The correct option is D Megaspore mother cell $\to$ Megaspore $\to$ Embryo sac

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. These 8 nuclei then get organized into egg apparatus (consisting of an egg cell and two synergids), a large central cell and three antipodal cells. This results in the formation of a 7-celled but 8-nucleate structure which is called the embryo sac.

Hence, the correct order of development of embryo sac is:

Megaspore mother cell $\to$ Megaspore $\to$ Embryo sac

So, the correct answer is D.