Question

Draw a neat diagram of a maize grain showing the internal structure and label any five parts.

Hint:

When labeling monocot seeds like maize, remember that protective sheaths always pair with specific embryonic tips: Coleoptile protects the Plumule (both contain 'p' for shoot), and Coleorhiza protects the Radicle (both contain 'r' for root).

Answer 1

Step 1: Understanding the Question:
The question requires drawing a clear anatomical diagram showing the internal longitudinal structure of a monocotyledonous maize grain (Zea mays), including at least five accurate structural labels.

Step 2: Key Formula or Approach:

A maize grain is a single-seeded fruit known as a caryopsis, where the protective seed coat is completely fused with the outer pericarp wall. It features a large endosperm storage region and a lateral embryo.

Step 3: Detailed Explanation:
A complete structural drawing of a maize grain includes the following key parts: 1. Pericarp + Seed Coat: The outermost protective layer, formed by the tight fusion of the fruit wall (pericarp) and the seed coat.
2. Aleurone Layer: A specialized, protein-rich outer cell layer that surrounds the bulky starch endosperm storage tissue.
3. Endosperm: The main nutrient storage tissue, filled with starch, which feeds the embryo during germination.
4. Scutellum: The large, shield-shaped single cotyledon characteristic of monocots, which absorbs nutrients from the endosperm.
5. Coleoptile: A protective sheath that encloses and shields the developing young shoot apex (plumule).
6. Plumule: The embryonic shoot tip that will grow into the primary stem and leaves.
7. Radicle: The embryonic root tip that will grow downward to form the root system.
8. Coleorhiza: A protective undifferentiated sheath that covers and shields the embryonic root tip (radicle).

Step 4: Final Answer:
The student should sketch the longitudinal section of the maize grain, showing the large endosperm separated from the embryo by the scutellum, with the coleoptile protecting the plumule and the coleorhiza protecting the radicle.