Question

1. describe the structure of a seed and an embryo. 2. how are the seeds of monocots different from the seeds of dicots? 3. how are the embryo and the endosperm formed? 4. what purpose does the endosperm serve in the seed?

Explanation:

1. A seed has a seed - coat for protection, an embryo which will develop into a new plant, and may have endosperm for nutrient storage. The embryo consists of the radicle (future root), plumule (future shoot), and cotyledons (seed - leaves).
2. Monocot seeds have one cotyledon, while dicot seeds have two. Monocot seeds often have endosperm that persists at maturity, and their cotyledon is specialized for absorbing nutrients from the endosperm. Dicot seeds usually use up the endosperm during development, and the two cotyledons store nutrients.
3. The embryo is formed from the zygote (fertilized egg) through a series of cell - division and differentiation events. The endosperm is formed by the fusion of a sperm nucleus with two polar nuclei in the central cell of the ovule (double - fertilization in angiosperms).
4. The endosperm serves as a source of nutrients (such as starch, proteins, and lipids) for the developing embryo during germination and early growth.

Answer:

1. A seed typically consists of a seed - coat, an embryo, and may have endosperm. The embryo contains the radicle, plumule, and cotyledons. The seed - coat protects the internal structures. The embryo is the young plant in an arrested state, and the endosperm (if present) stores nutrients.
2. Monocot seeds have one cotyledon and often have persistent endosperm. Dicot seeds have two cotyledons and usually use up the endosperm during development. The cotyledons in monocots are specialized for nutrient absorption from the endosperm, while in dicots, they store nutrients.
3. The embryo is formed from the zygote through cell - division and differentiation. The endosperm is formed by the fusion of a sperm nucleus with two polar nuclei in the central cell of the ovule (double - fertilization in angiosperms).
4. The endosperm provides nutrients (such as carbohydrates, proteins, and fats) to the embryo during germination and early growth.