Question

Draw a labelled diagram of mature dicot embryos.

Answer 1

Hint: Plant embryos have structures called cotyledons in plants. The central portion of the seed embryo to which the epicotyl in-the immature shoot and the radicle-the immature roots are attached is cotyledon.

Complete Answer:
- Plants are categorised according to the number of cotyledons in the embryo present. It is a monocotyledon plant if the embryo has one cotyledon (monocotyledon), and if there are two cotyledons (dicotyledon), it is a dicotyledon plant.
- Sections of the standard embryo dicot include: Plumule, cotyledon, hypocotyl, radical and root cap.
- A standard cotyledon embryo, consisting of an embryonic axis and two cotyledons.
- The portion of the embryonic axis above the cotyledon stage is epicotyl, which ends with the tip of the plumule or stem.
- The cylindrical part below the cotyledon stage is hypocotyl, which ends at its lower end in the radical or root tip. With a root cap, the tip of the root is sealed.
- Subdivision of Seed: Seeds can be subdivided into endosperm and non-endosperm, depending on the form and position of storage materials.
- Endospermic: Endospermic seeds are those which in the mature seed have an endosperm. It is fleshy, oily, surrounds the embryo, and acts as the sole organ of food storage. A thin and papery cotyledon is present within the seed cover. The plants of Monocot have endospermic seeds.
- Non-endospermic seeds: Non-endospermic seeds do not have an endosperm in the mature crop. Cotyledons are thick and fleshy, and are the only food storage organs. Dicot plants have non-endospermic seeds.

Note: Plant embryogenesis is a mechanism that occurs to produce a fully developed plant embryo following the fertilization of an ovule. This is a relevant step in the plant life cycle, followed by dormancy and germination. In order to become a mature embryo, the zygote formed after fertilization must undergo various cell divisions and differentiations.