Place the following stages into the correct sequence to represent the development of a eudicot embryo. Label the first step as 1, and the second step as 2, etc.
The Correct Answer and Explanation is:
To place the stages of eudicot embryo development in the correct order, let’s first break down the major steps involved:
- Fertilization: After double fertilization, the zygote and the endosperm are formed. The zygote develops into the embryo, while the endosperm provides nutrients to the developing embryo.
- Early Development (Globular Stage): The embryo begins to divide rapidly, forming a ball-like structure. The apical meristems, which will later form the shoot and root, are established in this stage.
- Heart Stage: At this stage, the embryo takes on a more recognizable shape resembling a heart. The cotyledons (seed leaves) begin to develop, and the root and shoot apical meristems become more distinct.
- Torpedo Stage: The embryo elongates and takes on a more torpedo-like shape. Cotyledons continue to expand and develop, and the embryo’s major body axis becomes more evident.
- Mature Embryo: The embryo is fully developed and is now capable of germinating once the seed conditions are favorable. The cotyledons are fully formed, and the shoot and root apical meristems are ready to drive the plant’s further growth.
Correct Order:
- Fertilization: Zygote and endosperm formation.
- Early Development (Globular Stage): Rapid cell division forming a ball-shaped structure.
- Heart Stage: Development of cotyledons and distinct root and shoot apical meristems.
- Torpedo Stage: Elongation of the embryo with visible cotyledons and axis formation.
- Mature Embryo: Fully developed with cotyledons and ready for germination.
Explanation:
Embryo development in eudicots involves a series of stages starting from fertilization, where the zygote begins to form. This is followed by early divisions resulting in a globular shape. The heart stage further refines the development with the appearance of cotyledons. During the torpedo stage, the embryo elongates, and by the mature stage, it is ready for seed germination. These stages reflect both the morphological changes and the functional differentiation that occurs to prepare the embryo for future growth.
