Question

State the chief function of each part of a pollen grain and an ovule

Answer 1

Pollen grains:

1. Pollen grains are referred to as male gametophytes.
2. It contains two male gametes in it.
3. Pollen grains consist of two outer coverings, exine, and intine.
4. In an outer layer, it has an opening referred to as a germ pore.
5. Inside the intine, the Tube cell and generative cell are located.

Structure of pollen grain:

Functions of the parts of pollen grain:

1. Exine - protects pollen grain from damage and desiccation.
2. Intine - plays role in pollen tube germination.
3. Tube cell - grows into the pollen tube
4. Generative cell - fuses with egg and carries out fertilization.
5. Tube cell nucleus - fused with polar nuclei and carry out double fertilization.

Ovule:

1. An ovule is a structural unit of the Female reproductive system of plants.
2. The ovule is referred to as a female gametophyte and it contains egg cells in it.
3. it has main three parts, Outer Integuments, middle nucellus, and inner embryo sac.
4. Integuments are double-layered, having a Micropylar opening.
5. Opposite to Micropyle, the basal Chalazal end is located.
6. The embryo sac is referred to as 7 celled, 8-nucleated structure.
7. The embryo sac contains one egg cell, two synergids, one central cell with two polar nuclei, and three antipodal cells.

Structure of ovule:

The function of the ovule:

1. Funicle - It serves as an attachment of the ovule to the placenta.
2. Integuments - They function as a protective covering for the ovule.
3. Micropyle - it allows a pollen tube to enter the ovule.
4. Nucellus - It provides nutrition to growing embryos.
5. Synergids - allow the growth of pollen tube into the embryo sac.
6. Antipodal cells - play a role in nutrition.
7. Egg cell - It fuses with a generative cell of male gamete and carries out fertilization.
8. Polar nuclei - fuses with tube cell nucleus of gametes and carry out double fertilization.