Sperm of Fern enters an archegonium due to

Options

A. Chemotaxy
B. Phototaxy
C. Thermotaxy
D. Cyclosis.

Answer

**Step-by-Step Solution:**

1. **Understanding the Context**: The question asks how the sperm of a fern enters the archegonium, which is the female reproductive structure in ferns. Ferns belong to the group known as pteridophytes.

2. **Identifying the Structures**: The archegonium consists of a swollen base called the venter and a long neck. The venter contains the egg cell, which is the female gamete.

3. **Mechanism of Sperm Entry**: The sperm, which is the male gamete, needs to reach the egg cell within the archegonium. This is facilitated by the secretion of chemicals from the neck of the archegonium.

4. **Role of Chemicals**: The neck of the archegonium releases specific chemicals that attract the sperm towards it. This attraction is crucial for the sperm to navigate and enter the archegonium.

5. **Terminology**: The process by which the sperm is attracted to the archegonium due to these chemical signals is known as "chemotaxy." This term specifically refers to movement in response to chemical stimuli.

6. **Eliminating Other Options**:
- **Phototaxy**: This term relates to movement in response to light, which is not applicable here.
- **Thermotaxy**: This refers to movement in response to temperature, which is also not relevant in this context.
- **Cyclosis**: This term describes the movement of cytoplasm within a cell and does not pertain to the movement of sperm towards the archegonium.

7. **Conclusion**: Based on the understanding of the mechanisms involved, the correct answer is "chemotaxy."

**Final Answer**: The sperm of fern enters an archegonium due to **chemotaxy**.

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