“Endostome” and “Exostome” are part of

Options

A. Nucellus
B. Pollen wall
C. Chalaza
D. micropyle

Answer

**Step-by-Step Solution:**

1. **Understanding the Ovule Structure**: The ovule is a crucial part of the flowering plant's reproductive system. It contains the female gametes and is surrounded by integuments, which are protective layers.

2. **Identifying the Openings**: At the tip of the ovule, there is an opening known as the micropyle. This opening is essential for the entry of the pollen tube during fertilization.

3. **Defining Endostome and Exostome**:
- The **endostome** refers to the opening of the ovule that is formed by the inner integument.
- The **exostome** refers to the opening formed by the outer integument.

4. **Types of Ovules**:
- In a **Biotagmic Ovule**, the opening is primarily made by the inner integument, which is why it is referred to as the endostome.
- If the opening is made by the outer integument, it is called the exostome.
- When both integuments contribute to the formation of the opening, it is termed **amphistome**.

5. **Conclusion**: Based on the definitions, "endostome" and "exostome" are parts of the ovule, specifically related to the integuments that form the openings for pollen tube entry.

**Final Answer**: Endostome and Exostome are parts of the ovule.

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