Hydra will regnerate from a fragment, if it contain

Options

A. Tentacles
B. Epidermis and gastrodermis
C. Tentacles, epidermis and gastrodermis
D. Epidermis, hypodermis and gastrodermis.

Answer

**Step-by-Step Solution:**

1. **Understanding Hydra's Regeneration:** Hydra is known for its remarkable ability to regenerate. This means that if a part of Hydra is cut or damaged, it can regrow that part.

2. **Identifying Germ Layers:** Hydra is a diploblastic organism, which means it has two primary germ layers:
- **Ectoderm:** This layer forms the epidermis (the outer layer of cells).
- **Endoderm:** This layer forms the gastrodermis (the inner layer that lines the digestive cavity).

3. **Fragments and Their Components:** For Hydra to regenerate from a fragment, that fragment must contain both the epidermis and gastrodermis. This is because both layers are essential for the formation of new tissues and structures.

4. **Evaluating the Options:**
- **Option 1: Tentacles** - This is incorrect because tentacles alone do not contain the necessary layers for regeneration.
- **Option 2: Epidermis and Gastrodermis** - This is correct because these two layers are essential for regeneration.
- **Option 3: Tentacles, Epidermis, and Gastrodermis** - This is incorrect because while it includes the correct layers, the tentacles alone do not suffice for regeneration.
- **Option 4: Epidermis, Hypodermis, and Gastrodermis** - This is incorrect because Hydra does not have a hypodermis; it only has epidermis and gastrodermis.

5. **Conclusion:** The correct answer is **Option 2: Epidermis and Gastrodermis**. These two layers are necessary for Hydra to regenerate from a fragment.

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