Question

In gymnosperm the pollen chamber represents?

• A. Microsporangium in which pollen grains develop
• B. A cavity in the ovule in which pollen grains are stored after pollination
• C. A cell in the pollen grain in which the sperms are formed
• D. An opening in the megagametophyte through which the pollen tube approaches the egg

Answer 1

The correct option is B

A cavity in the ovule in which pollen grains are stored after pollination

The correct option is B.

The explanation for the correct option:

1. The space in the ovule where pollen grains are placed after pollination is known as the pollen chamber in gymnosperms.
2. Within the pollen chamber, the generative cell nucleus divides into two gametic nuclei, and the cell of the tube lengthens to produce the pollen tube.
3. Gymnosperms have a hollow in their ovules called the pollen chamber, which is where pollen grains are deposited following pollination.
4. Within the pollen chamber, the generative cell nucleus divides into two gametic nuclei, and the cell of the tube lengthens to produce the pollen tube.
5. The pollen tube enters the female gametophyte and is filled with gametic nuclei (also known as sperm nuclei).
6. One of these creates the zygote when it fuses with the female gamete (oosphere) (2n).

Explanation for incorrect options:

Option A:

1. The anther is where pollen grains (male gametophytes) develop.
2. When specialised cells (microsporocytes) begin to differentiate in immature anthers, pollen formation can begin.
3. Each microsporocyte, which often numbers hundreds or thousands, undergoes meiosis to produce four haploid microspores.

Option C:

1. The generative cell is created at the initial microspore division and divides to produce two sperm cells in the pollen grain or pollen tube.
2. The generative cell is therefore never truly "free” of the vegetative cell it is embedded in.

Option D:

1. Megagametophyte, which emerges from the megaspores of heterosporous plants, is the female gametophyte.
2. For instance, the sporophyte plant generates megaspores that are loaded with food among heterosporous species of lycophyte plants.
3. Megagametophytes that form from these spores lay eggs.
4. Therefore, the Filiform apparatus serves the purpose of directing and drawing pollen tubes.
5. Megagametophytes (embryo sacs) form in the ovary's ovules, which are where they are found.
6. In the pollen sacs (microsporangia) of the anther, pollen grains (microgametophytes) grow.
7. Each ovule contains one megaspore mother cell, which goes through meiosis and normally produces one functioning megaspore.

Final answer: In gymnosperm, the pollen chamber represents a cavity in the ovule in which pollen grains are stored after pollination.