Ovule

Definition

An ovule is a structure found in seed plants that contains the female gametophyte and develops into a seed after fertilization. It is critical for sexual reproduction as it houses the egg cell and, upon successful fertilization, transforms into a seed, ensuring the continuation of the plant species. The evolution of ovules marked a significant advancement in plant reproduction, providing protection to the developing embryo and facilitating the transition to seed plants.

5 Must Know Facts For Your Next Test

1. Ovules are typically located within the ovary of a flower or cone and are produced by ovulate structures called ovules or megasporangia.
2. In gymnosperms, ovules are often exposed on the surface of cone scales, while in angiosperms, they are enclosed within the ovary until fertilization occurs.
3. Once fertilized, an ovule develops into a seed, containing an embryo that can remain dormant until conditions are favorable for germination.
4. The protective integuments surrounding an ovule play a crucial role in safeguarding the developing embryo from environmental stresses.
5. Ovules are essential for the genetic diversity of plant populations, as they facilitate cross-pollination and genetic mixing through sexual reproduction.

Review Questions

• How does the structure and function of an ovule contribute to the reproductive success of seed plants?
  • The structure of an ovule is designed to protect the female gametophyte and developing embryo. By encapsulating these vital components within protective integuments, ovules enhance reproductive success by reducing environmental risks during development. This protection, combined with the ability of seeds to remain dormant until conditions are suitable for growth, allows seed plants to thrive in various environments.
• Compare the differences in ovule development between gymnosperms and angiosperms and explain their evolutionary significance.
  • In gymnosperms, ovules are typically exposed on the surface of cones, making them vulnerable to environmental factors but allowing for wind pollination. Conversely, angiosperms enclose their ovules within ovaries, providing additional protection and facilitating more complex interactions with pollinators. This evolutionary adaptation has enabled angiosperms to dominate terrestrial ecosystems due to increased seed protection and successful reproductive strategies.
• Evaluate the role of ovules in promoting genetic diversity among plant species and their impact on ecosystem dynamics.
  • Ovules play a crucial role in promoting genetic diversity through sexual reproduction, enabling cross-pollination and genetic mixing. This genetic variation enhances a population's adaptability to changing environmental conditions and contributes to ecosystem stability. As plant species interact with various pollinators and adapt to their habitats via diverse offspring, ovules thus support not only individual species' survival but also overall ecosystem health and resilience.

Related terms

Seed:

A mature ovule containing an embryo, stored nutrients, and a protective seed coat, allowing for the dispersal and potential growth of a new plant.

Megasporangium: A structure that produces megaspores, which develop into female gametophytes and eventually lead to ovule formation in seed plants.

Fertilization:

The process by which male and female gametes unite, leading to the formation of a zygote, which subsequently develops into an embryo within the ovule.