Common between trichocysts of Paramecium and nematocysts of Hydra is

Options

A. Attachment and defence
B. Defence only
C. Sensitivity
D. Food capturing.

Answer

**Step-by-Step Solution:**

1. **Understanding Trichocysts in Paramecium:**
- Trichocysts are small, rod-like structures found in Paramecium.
- Their primary function is to provide protection against predators and other dangers.
- They can discharge filaments that can entangle or deter potential threats, serving as a defense mechanism.

2. **Understanding Nematocysts in Hydra:**
- Nematocysts are specialized cells found in Hydra, which is a member of the phylum Coelenterata (or Cnidaria).
- These cells contain a coiled, harpoon-like structure that can inject toxins into prey or threats.
- Like trichocysts, nematocysts also serve a defensive purpose, protecting Hydra from predators and aiding in capturing prey.

3. **Comparing Functions:**
- Both trichocysts and nematocysts serve a defensive function.
- While nematocysts can also assist in food capture, trichocysts do not have this role.

4. **Evaluating the Options:**
- **Option A: Attachment and defense** - Incorrect, as attachment is not a function of either structure.
- **Option B: Defense only** - Correct, as both structures primarily serve in defense.
- **Option C: Sensitivity** - Incorrect, as neither structure is primarily involved in sensitivity.
- **Option D: Food capturing** - Incorrect for trichocysts, as they do not capture food.

5. **Conclusion:**
- The common function between trichocysts of Paramecium and nematocysts of Hydra is primarily defense.

**Final Answer:** B) Defense only

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