' Contractile vacuole ' play important role in excretion in

Options

A. Amoeba
B. Paramecium
C. Hydra
D. both (A)&(B)

Answer

**Step-by-Step Solution:**

1. **Understanding the Role of Contractile Vacuoles:**
- Contractile vacuoles are specialized structures found in certain unicellular organisms. Their primary function is to regulate the amount of water within the cell, which is crucial for maintaining osmotic balance.

2. **Identifying Organisms with Contractile Vacuoles:**
- The question lists four organisms: amoeba, paramecium, hydra, and both A and B. We need to determine which of these organisms utilize contractile vacuoles for excretion.

3. **Analyzing Each Option:**
- **Amoeba:** Amoeba possesses contractile vacuoles that help in excretion and osmoregulation. They expel excess water that enters the cell through osmosis.
- **Paramecium:** Paramecium also has contractile vacuoles that serve a similar function as in amoeba, aiding in the removal of excess water and waste.
- **Hydra:** Hydra does not have contractile vacuoles. Instead, it primarily excretes waste through diffusion across its body surface, as it is a multicellular organism with a different excretion mechanism.

4. **Conclusion:**
- Since both amoeba and paramecium utilize contractile vacuoles for excretion, the correct answer to the question is option four: "both A and B."

**Final Answer:**
The contractile vacuole plays an important role in excretion in both amoeba and paramecium.

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