Q.Embryo sac is to ovule as _______ is to an anther.

The embryo sac represents the female gametophyte, which is a multicellular structure that develops inside the ovule. The ovule, therefore, serves as the protective and nutritive environment for the female gametophyte.

Following this analogy, we need to identify the male gametophyte that develops within the anther. The anther is the part of the stamen responsible for producing pollen. Each pollen grain is the male gametophyte, containing the male gametes. Thus, the pollen grain develops inside the anther, just as the embryo sac develops inside the ovule.

To understand this analogy, we need to clarify the roles of the male and female reproductive structures in flowering plants, specifically focusing on where the actual gamete-producing structures, or gametophytes, are located.

In a flower, the female reproductive part is the pistil or carpel, which typically consists of an ovary, style, and stigma. Inside the ovary, one or more ovules are present. The ovule is a small, oval structure attached to the placenta within the ovary. It is within this ovule that the female gametophyte develops.

The female gametophyte, also known as the embryo sac, is a microscopic structure that develops from a single functional megaspore inside the ovule. A mature embryo sac is typically a 7-celled, 8-nucleate structure. It contains the egg cell, which is the actual female gamete, along with synergids, antipodal cells, and a central cell with two polar nuclei. Thus, the embryo sac is the specific structure within the ovule that houses the egg cell and is the site of fertilization.

On the male side, the reproductive organ is the stamen, which comprises two main parts: a long, slender filament and a terminal, bilobed structure called the anther. The anther is the crucial part where pollen is produced.

Inside the anther, there are usually four microsporangia, often referred to as pollen sacs. These pollen sacs contain numerous microspore mother cells, which undergo meiosis to produce microspores. Each microspore then develops into a pollen grain.

A mature pollen grain typically consists of two cells: a larger vegetative cell and a smaller generative cell. The generative cell later divides to form two male gametes. The pollen grain is released from the anther and is responsible for carrying these male gametes to the stigma of a flower for fertilization.

Now, let's apply this understanding to the analogy: "Embryo sac is to ovule as _______ is to an anther."

• The ovule is the larger structure that contains the female gametophyte (the embryo sac).
• Following this pattern, the anther is the larger structure that contains the male gametophyte.

Therefore, the structure that is analogous to the embryo sac (the female gametophyte within the ovule) is the male gametophyte found within the anther. This male gametophyte is the pollen grain.

Let's briefly consider why the other options are incorrect:

• (A) Stamen: This refers to the entire male reproductive unit, consisting of both the anther and the filament. It is a larger organ, not the gametophyte itself.
• (B) Filament: This is merely the stalk that supports the anther. It does not contain the gametes or the gametophyte.
• (D) Androecium: This is the collective term for all the stamens in a flower. It represents the entire male whorl, not a specific gametophyte.

The analogy holds true: the ovule contains the embryo sac, just as the anther contains the pollen grain.