If an Amoeba is placed in distilled water, its contractile vacuole

Options

A. works slowly
B. works faste
C. disappears
D. divides

Answer

To solve the question regarding the behavior of the contractile vacuole in an Amoeba when placed in distilled water, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Function of the Contractile Vacuole**:
- The contractile vacuole in Amoeba is responsible for osmoregulation, which involves the expulsion of excess water from the cell.

2. **Define Distilled Water**:
- Distilled water is a hypotonic solution, meaning it has a lower concentration of solutes (like salts) compared to the internal environment of the Amoeba.

3. **Effect of Placing Amoeba in Distilled Water**:
- When the Amoeba is placed in distilled water, water enters the cell through osmosis because the concentration of solutes inside the cell is higher than that in the distilled water.

4. **Process of Water Entry**:
- The process by which water enters the cell is called endosmosis. As water enters, it fills the contractile vacuole.

5. **Function of the Contractile Vacuole**:
- As the contractile vacuole fills with water, it expands. Once it reaches the edge of the cell, it contracts and expels the excess water outside the cell.

6. **Repetition of the Process**:
- This process of filling and expelling water continues as long as the Amoeba remains in the hypotonic environment of distilled water.

7. **Conclusion**:
- Given that the contractile vacuole is actively working to expel water to prevent the Amoeba from bursting, we can conclude that the contractile vacuole works fast in this scenario.

### Final Answer:
The correct answer is that the contractile vacuole **works fast** when an Amoeba is placed in distilled water.

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