MCQ Detailed View

The seed coat is the outer protective covering of a seed, and it is also called the testa. Its primary function is to safeguard the embryo inside the seed from physical damage, pathogens, and unfavorable environmental conditions. Without this protective covering, seeds would be more vulnerable to drying out, mechanical injury, or attacks by insects and microorganisms.

The seed coat develops from the integuments of the ovule after fertilization. In most plants, the seed coat is tough and rigid, providing durability to the seed until conditions are right for germination. This protective layer ensures that the seed can remain dormant for extended periods and survive in harsh environments.

Seeds may sometimes have two layers of protection: the testa (outer coat) and the tegmen (inner coat). The testa is usually thicker and harder, while the tegmen is thinner and delicate. Together, they form a protective barrier around the seed. However, in common usage, the term seed coat generally refers to the outer layer, the testa.

Another important role of the seed coat is to control water absorption during germination. The seed cannot sprout until it absorbs sufficient water, and the testa regulates this process. In some seeds, the coat must be broken, softened, or scarified (scratched) before water can enter. This mechanism prevents premature germination in unsuitable conditions.

It is important not to confuse the seed coat (testa) with the radicle, which is the embryonic root, or the cotyledons, which are food storage structures.

In summary, the outer protective layer of a seed is known as the testa, and it plays a crucial role in protecting the embryo, maintaining dormancy, and ensuring successful germination when the environment becomes favorable.