Question

Which one is the female gamete in embryo sac?
A. Synergid
B. Antipodal cell
C. Oosphere
D. Central cell

Answer 1

Hint: The embryo sac is the megaspore of a plant that bears the seeds. It is located within the ovule which is giving rise to the endosperm that produces the egg cell or nucleus from which the embryo plant is grown after fertilization.

Complete answer:
Double fertilization is a type of complex fertilization which mechanism is found in the flowering plants or the angiosperms. In this mechanism, a female gametophyte which is also known as the embryo sac involves joining with two male gametes which are called sperm. This process of fertilization starts when a pollen grain is attached to the stigma of the carpel which is the female reproductive structure of a flower. The pollen grain then germinates and forms a pollen tube that extends down toward the ovary through style. Further, this pollen tube proceeds to release the two sperms. The cells of an ovule that remain unfertilized are eight in number and they are three antipodal cells, two central cells, two synergids, and one egg cell.

From the above given options:
> Option A: Synergids are the haploid cells. Two synergid cells are found in the side of the egg cell and along with the egg cell they composed the egg apparatus which is present at the micropylar end of the embryo sac. These synergids secrets are some attractant and due to this the pollen tube comes into the style.

> Option B: Antipodal cells generally can be noticed at the chalazal pole of the embryo sac. There are three antipodal cells.

> Option C: The Oosphere is the cell or ovum which is present in the female reproductive part. In seeded plants, the Oosphere contains the egg. The egg is present in the embryo sac.

> OPtion D: The central cell is a diploid cell that is found in the center of the embryo sac. This central cell is made up of two polar nuclei that get fused and generate a diploid secondary nucleus. When the central cell gets fused with the male gamete then it leads to the formation of a triploid primary endosperm mother cell.

Hence, the correct answer is option (C).

Note: In the embryo sac, generally, there are two female gametes found, one is an egg cell and the other is a central cell. The egg cell possesses a single nucleus while the central cell possesses two haploid nuclei which are known as the polar nuclei. These two female gametes i.e. the egg and the central cell with two polar nuclei directly take part in the process of fertilization. During fertilization, one sperm cell gets fused with the egg and forms a zygote. Later the second sperm cell produces the triploid primary endosperm nucleus.