The membrane by which vacuoles are bound is ________.

Explanation

**Step-by-Step Solution:**

1. **Identify the Structure**: The question asks about the membrane that surrounds vacuoles. We need to identify what this membrane is called.

2. **Define Vacuoles**: Vacuoles are membrane-bound organelles found in the cells of plants and some other organisms. They are important for storage and maintaining the cell's internal environment.

3. **Identify the Membrane**: The membrane that surrounds vacuoles is known as the "Tonoplast."

...