Question

A typical angiosperm embryo sac at maturity is:

• A. 7-nucleate and 8-celled
• B. 8-nucleate and 7-celled
• C. 7-nucleate and 7-celled
• D. 8-nucleate and 8-celled

Answer 1

The correct option is B

8-nucleate and 7-celled

The correct option is B

Explanation of correct option:

1. Angiosperms refer to plants in which the seed is enclosed within the ovary. Example: mango, apple.
2. In angiosperms, the ovule contains an embryo sac (female gametophyte) which is formed from a megaspore.
3. The nucleus of the megaspore divides mitotically and gives rise to a 2-nucleate embryo sac. This is followed by two more nuclear divisions, resulting in the formation of a 4-nucleate and later an 8-nucleate embryo sac.
4. In the embryo sac, there are seven cells- one central cell, two synergids, one egg cell, and three antipodals. The egg apparatus comprising a group of three cells (two synergids and one egg cell) is found at the micropylar end. Three antipodal cells are located at the chalazal end. Six of the eight nuclei are enclosed by cell walls, whereas, the remaining two nuclei (polar nuclei) are located in the central cell. Hence, a typical angiosperm embryo sac at maturity is 8-nucleate and 7-celled.

Final answer: A typical angiosperm embryo sac at maturity is 8-nucleate and 7-celled.