Question

Embryo sac occurs in
A) Embryo
B) Axis part of embryo
C) Ovule
D) Endosperm

Answer 1

Embryo sac is the female gametophyte found in seed plants that consist of a sac i.e. thin walled within the nucellus.

Complete answer:
Ovule is a structure which gives rise and can contain a female reproductive cell. Embryo sac is produced in ovule by the megasporogenesis process and by the process of megagametogenesis. During the megasporogenesis process, a megaspore mother cell that is diploid in nature goes through meiosis and as a result it forms four spores that are haploid. These are also called megaspores. Between the four megaspores, three of them undergo degeneration and the rest one remains functional. The rest megaspore is then further developed into female gametophyte or embryo sac. The formation of the female gametophyte is also called megagametogenesis. These megaspore nuclei can undergo meiotic divisions and there is no need to form a cell wall. The meiosis takes place three times in this stage which results in the formation of eight nuclei. These nuclei are organized into egg apparatus, 3 of them make antipodal cells and the rest are the central cell. This is the form of a 7-celled or 8-nucleate embryo structure that is the female gametophyte. At the time of fertilization, the megagametophyte gives rise to the formation of egg cells.
Hence, Option “C” Ovule is the correct answer.

Note: The embryo sac contains egg nucleus and the nucleus that further gives rise to endosperm at the time of fertilization.