In the embryos of a typical dicot and a grass, true homologous structures are

Options

A. coleorhiza and coleoptile
B. coleoptile and scutellum
C. cotyledons and scutellum
D. hypocotyl and radicle

Answer

To solve the question regarding true homologous structures in the embryos of a typical dicot and a grass (monocot), we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Understanding the Structures**:
- **Coleorhiza**: This is a protective sheath that surrounds the radical (embryonic root) in monocots.
- **Coleoptile**: This is a protective sheath that surrounds the plumule (embryonic shoot) in monocots.
- **Cotyledons**: These are the first leaves that develop from the embryo. In dicots, there are typically two cotyledons.
- **Scutellum**: This is a single, shield-shaped cotyledon found in monocots, particularly in grasses.
- **Hypocotyl**: This is the part of the embryo that lies between the cotyledons and the radical.
- **Radical**: This is the part of the embryo that develops into the root.

2. **Analyzing Each Option**:
- **Option 1: Coleorhiza and Coleoptile**: Both structures are found in monocots. They are not homologous to any structure in dicots. **(Not the correct option)**
- **Option 2: Coleoptile and Scutellum**: Both are structures in monocots. Coleoptile protects the plumule, while scutellum is a cotyledon. They are not homologous to any structures in dicots. **(Not the correct option)**
- **Option 3: Cotyledons and Scutellum**: Cotyledons are found in dicots (two in number), while scutellum is a single cotyledon in monocots. Although they serve similar functions (food storage), they are not homologous structures. However, they are the closest match in terms of function and origin. **(Correct option)**
- **Option 4: Hypocotyl and Radical**: The hypocotyl is part of the embryo in dicots, while the radical is the root part in both dicots and monocots. They are not homologous structures. **(Not the correct option)**

3. **Conclusion**:
- After analyzing all the options, the true homologous structures in the embryos of a typical dicot and a grass (monocot) are **Cotyledons and Scutellum**. Therefore, the correct answer is **Option 3**.