The structure which replaces the nucellus in Pinus ovule is

Options

A. Embryo
B. Endosperm
C. Perisperm
D. None of the above.

Answer

To solve the question regarding the structure that replaces the nucellus in the Pinus ovule, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: Pinus is a genus of gymnosperms, which are plants that produce seeds that are not enclosed in an ovary (naked seeds).

2. **Identify the Components of the Ovule**: In the ovule of Pinus, the nucellus is a parenchymatous tissue that serves as a nutritive tissue for the developing embryo.

3. **Know What Happens After Fertilization**: After fertilization occurs, the nucellus is replaced by a structure that provides nutrition to the developing embryo.

4. **Identify the Correct Structure**: The structure that replaces the nucellus after fertilization in gymnosperms, including Pinus, is called the endosperm. The endosperm is the female gametophyte that provides nourishment to the embryo.

5. **Evaluate the Options**:
- **Embryo**: This is formed after fertilization but does not replace the nucellus.
- **Endosperm**: This is the correct answer as it replaces the nucellus.
- **Perisperm**: This is a remnant of the nucellus but does not replace it.
- **None of the Above**: This option is incorrect since we have identified the endosperm.

6. **Conclusion**: Therefore, the structure that replaces the nucellus in the Pinus ovule is the endosperm.

### Final Answer:
The structure which replaces the nucellus in Pinus ovule is **endosperm**.

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