Investigate and describe the structure of a seed, limited to embryo (radicle, plumule and cotyledons) and testa

Sourav PanNovember 3, 2024

Answered

The structure of a seed is a crucial aspect of plant reproduction, consisting primarily of the embryo and the seed coat (testa). Here’s a detailed description of these components:

Structure of a Seed

1. Embryo:
   The embryo is the developing plant contained within the seed and consists of several key parts:
   • Radicle: This is the embryonic root that will develop into the primary root of the plant. It anchors the plant in the soil and absorbs water and nutrients.
   • Plumule: The plumule is the embryonic shoot that will develop into the stem and leaves of the plant. It is responsible for photosynthesis once the plant emerges from the soil.
   • Cotyledons: These are the seed leaves that provide nourishment to the developing embryo. In some seeds, such as beans, cotyledons are large and fleshy, storing nutrients for the seedling until it can perform photosynthesis.
2. Testa (Seed Coat):
   The testa is the outer protective layer of the seed. It serves several important functions:
   • Protection: The testa protects the internal structures of the seed from physical damage, pathogens, and desiccation (drying out).
   • Dormancy Regulation: The seed coat can prevent premature germination by blocking water and gas exchange until conditions are favorable for growth.
   • Micropyle: An opening in the testa known as the micropyle allows water to enter during germination. It is also where the pollen tube enters during fertilization, facilitating sperm delivery to the ovule.