Question

State the chief function of each part of an ovule.

Answer 1

Ovule:

1. An ovule is a structural unit of the Female reproductive system of plant.
2. The ovule is referred to as a female gametophyte and it contains egg cells in it.
3. It gives rise to seed after fertilization.

Structure of the ovule:

1. The ovule is attached to the placenta by means of a stalk-like structure, referred to as Funicle.
2. The point of attachment of Funicle is referred to as Hyrum.
3. The outer layer of the ovule is known as the integument.
4. They are two integuments, inner integument, and outer integument.
5. There is a small opening in Integuments, referred to as Micropyle.
6. The micropyle is referred to as the top end of the ovule.
7. Opposite to Micropyle, the basal end is located, referred to as Chalaza.
8. Inner to the integument, Nucellus is present.
9. The nucellus is a fluid-like structure consisting of an embryo sac.
10. The embryo sac is referred to as 7 celled, 8-nucleated structure.
11. Towards the Micropylar end, egg cells and two synergids are observed.
12. Towards the chalazal end, three antipodal cells are observed.
13. At the center, a central cell is present.
14. The central cell has two polar nuclei.

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 male gamete and carries out fertilization.
8. Polar nuclei - fuses with other male gametes and carry out double fertilization.